CSIRO PUBLISHING
Sexual Health, 2014, 11, 383–396 http://dx.doi.org/10.1071/SH14115
Design and methods of the Second Australian Study of Health and Relationships Juliet Richters A,J, Paul B. Badcock B,C, Judy M. Simpson D, David Shellard E, Chris RisselF, Richard O. de VisserG, Andrew E. GrulichH and Anthony M. A. Smith B,I A
School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW 2052, Australia. B Australian Research Centre in Sex, Health and Society, La Trobe University, 215 Franklin Street, Melbourne, Vic. 3000, Australia. C Centre for Youth Mental Health, University of Melbourne, Orygen Youth Health Research Centre, 35 Poplar Road, Parkville, Vic. 3052, Australia. D Sydney School of Public Health, Edward Ford Building (A27), University of Sydney, Sydney, NSW 2006, Australia. E Hunter Valley Research Foundation, PO Box 322, Newcastle, NSW 2300, Australia. F Sydney School of Public Health, Charles Perkins Centre (D17), University of Sydney, Sydney, NSW 2006, Australia. G School of Psychology, Pevensey 1, University of Sussex, Falmer BN1 9QH, UK. H The Kirby Institute, Wallace Wurth Building, University of New South Wales, Sydney, NSW 2052, Australia. I Deceased. J Corresponding author. Email: [email protected]
Abstract. Background: This paper describes the methods and process of the Second Australian Study of Health and Relationships. Methods: A representative sample of the Australian population was contacted by landline and mobile phone modified random-digit dialling in 2012–13. Computer-assisted telephone interviews elicited sociodemographic and health details as well as sexual behaviour and attitudes. For analysis, the sample was weighted to reflect the study design and further weighted to reflect the location, age and sex distribution of the population at the 2011 Census. Results: Interviews were completed with 9963 men and 10 131 women aged 16–69 years from all states and territories. The overall participation rate among eligible people was 66.2% (63.9% for landline men, 67.9% for landline women and 66.5% for mobile respondents). Accounting for the survey design and adjusting to match the 2011 Census resulted in a weighted sample of 20 094 people (10 056 men and 10 038 women). The sample was broadly representative of the Australian population, although as in most surveys, people with higher education and higher status occupations were overrepresented. Data quality was high, with the great majority saying they were not at all or only slightly embarrassed by the questionnaire and almost all saying they were 90–100% honest in their answers. Conclusions: The combination of methods and design in the Second Australian Study of Health and Relationships, together with the high participation rate, strongly suggests that the results of the study are robust and broadly representative of the Australian population. Additional keywords: methodology, national survey, random sampling, sexual behavior, telephone survey. Received 16 June 2014, accepted 3 September 2014, published online 7 November 2014
Introduction The first Australian Study of Health and Relationships (ASHR1) was the largest and most comprehensive population-based survey of sexuality ever undertaken in Australia and one of the largest in the world.1 Conducted in 2001–02, it emerged from a context of increasing interest in people’s sexual behaviour throughout the world, motivated largely by the rise and spread of the global HIV/AIDS epidemic in the 1980s and Journal compilation CSIRO 2014
1990s. Beyond HIV risk, the scholarly interest in sexual behaviour now includes sexual experiences and lifestyles. Overseas studies, most notably the British,2 American3 and French4 national surveys, combined sociological, sexological and epidemiological expertise to provide nationwide representative data. The need for an Australian national sex survey had been recognised by social and behavioural scientists, public health www.publish.csiro.au/journals/sh
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researchers and health policy planners in the 1990s. In response to this need, and drawing on the work done by the British,2 Americans3 and French,4 ASHR1 aimed to: provide a representative national population-based prevalence study of the sexual health and practices of Australian adults; identify the frequency and extent of sexually transmissible infection (STI) and HIV risk practices and the social, demographic and behavioural characteristics associated with such practices; and identify attitudes and current levels of knowledge regarding STIs and HIV/AIDS.1 The findings have been used widely in health policy and health promotion, research and clinical care. At the same time, a smaller representative sample survey, using similar methods,5 produced results broadly similar to those of ASHR1.6–8 Before ASHR1, apart from clinical studies, behavioural sex research in Australia consisted mostly of convenience-sample surveys of at-risk groups such as gay and other homosexually active men,9–14 lesbian, bisexual and other women in contact with the gay community,15 transgender people,16 sex workers17 and sexual health clinic clients, as well as groups of ongoing concern such as young people.18 This approach had served well to support community-based HIV-prevention programs, especially among gay men. However, the degree to which these studies validly represented the groups they surveyed was unknown. For example, were the capital-city periodic surveys of homosexually active men representative of such men in general, or skewed towards the more community-attached gay men? Comparing such groups with the gay-identified and homosexually active men in ASHR1 allowed researchers to assess the representativeness of convenience samples and thus increase their value for planning campaigns and predicting health service needs and infection risks at a population level.19 Probability sampling had been used before ASHR1 to survey secondary school20 and technical college students.21 During the 2000s, several sexual health surveys of the Australian population were carried out, such as the Australian Longitudinal Study of Health and Relationships,22 a smaller cohort study focusing on people in regular relationships. Further nationally representative surveys of secondary school students also took place.23,24 Other population-based studies such as the Household, Income and Labour Dynamics in Australia survey (www.melbourneinstitute. com/hilda, accessed 15 September 2014) also collect some information relevant to reproductive and sexual health, as does the Australian Longitudinal Study on Women’s Health (www.alswh.org.au, accessed 15 September 2015).25,26 The aims of the Second Australian Study of Health and Relationships (ASHR2) were to build on this body of knowledge by: (1) providing a representative national population-based study of the sexual and reproductive health of Australian adults aged 16–69 years; (2) describing changes in the sexual and reproductive health of Australian adults aged 16–59 years between 2001–02 and 2012–13 by comparing the ASHR1 data with current patterns; and (3) providing the first large-scale national data addressing the sexual health of Australian men and women aged 60–69 years. The decision to extend the age range of respondents to include people aged 60–69 years was based on the lack of information on the sexual health and behaviour of older groups27 and to enable us to compare them with those aged 50–59 years
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in ASHR1. Although Australia’s ageing population makes the sexual health of older people a mainstream issue for policy and practice, we did not attempt to include people over 70 years, as this would have required major changes in the questionnaire and in the recruitment methods to include those not living in households (e.g.those in aged care institutions). Methodology of ASHR2 Sampling We used dual-frame modified random-digit dialling (RDD) to recruit a sample for interview, combining traditional directoryassisted landline-based RDD with RDD of mobile telephones. Although there is continuing debate about the relative merits of RDD and sampling from directories,28,29 relying on directories alone precludes sampling of the mobile-only population and households with silent or unlisted numbers. The use of both a landline and mobile phone sampling frame was motivated by recent changes in Australian telecommunication patterns. At the time of ASHR1, over 97% of Australian households had a landline telephone.30 Recently, however, the representativeness of landline surveys has been challenged by the rise of mobile phone use and the decline in the proportion of households with fixed telephone lines that are used for incoming calls.31,32 Although not as high as the US figure of 34%,33 an Australian estimate from the time of ASHR2 indicated that in 2012, approximately 20% of adults lived in households without a fixed line telephone.34 The inability of landline-based surveys to reach such a substantial proportion of the population introduces an important bias.35–37 A further complication arises from the usage patterns of those who have access to both landlines and mobile phones,35 with non-response bias likely to be further exacerbated by landline householders who rely chiefly on their mobile for communication.38 Mobile-only users differ from those with landlines in demographic characteristics, attitudes and healthrelated behaviours.32,33,35,39–41 The modified RDD used for this study was as follows. Two landline samples and one mobile sample were randomly extracted from the electronic White Pages. Subsequently, the samples were modified by adding a small, randomly generated value to the telephone number, a method which produces a set of numbers that quite closely maps the Australian population. The final sample of numbers was compared with listed business numbers and any matches were deleted. Although this was more efficient than simple RDD, we still had to generate 185 600 different telephone numbers in order to obtain 20 127 interviews. Each randomly generated landline telephone number was linked to the electronic White Pages telephone directory and when a match was identified, an adjacent number was extracted with its corresponding household address. Households were then notified by letter that their number had been generated and that they would receive a telephone call. Addresses were identified for 36.6% of the landline telephone numbers generated by the RDD procedure. Using letters to forewarn households of an impending telephone call improves response rates,42,43 partly by increasing the perceived legitimacy of the survey. The letter explained the purpose and nature of the study, together with
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the names of the universities involved and the contact details for the lead researcher and the relevant ethics committee secretariat for further information. After a prospective respondent was selected, the interviewer explained the study, stressing that it was anonymous and voluntary and that the respondent could decline to answer any questions if s/he wished. Consent was obtained verbally with the questions ‘Do I have your consent to proceed? Is it OK to talk to you now?’. Up to six initial contact calls were made to each mobile and landline number. If any contact was made with a landline, a further five calls were made. For mobiles, at least five calls were made; 5% of mobile interviews required more than 10 calls to complete. When a selected telephone number was answered, the interviewer introduced the study. Calls to landlines were introduced as either the ‘Australian Study of Men’s Health and Relationships’ or ‘. . . Women’s Health and Relationships’, as this single-sex mode of recruitment has been found to elicit higher response rates. The person answering the landline was asked how many men (or women) between the ages of 16 and 69 years lived in the household. If there was more than one eligible resident, the computer-assisted telephone interview (CATI) program randomly selected the interviewee using an age-order protocol to prevent respondents self-selecting. When a mobile phone was answered, it was assumed to be the speaker’s own phone and the male or female questionnaire was selected. Respondents who requested more information about the study than was presented in the introduction could have it read to them or they could receive a letter via email, fax or mail, or they could consult the website; the last option was the most common way that respondents validated the study. Female interviewers employed by the Hunter Valley Research Foundation conducted all interviews. A male
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interviewer was available but never requested. All interviews were conducted in English. The interviews We chose telephone interviews rather than face-to-face interviews for ASHR1 because they allow greater privacy, do not require high levels of literacy and provide an efficient method that allows for quality control throughout the entire process of data collection.1,42,44 The potential for interviewer bias is also lower in telephone interviews because of the lack of face-to-face contact and the inability of participants to respond to non-verbal cues from interviewers.1,44 Finally, the low population density in Australia rendered the cost of face-toface interviews prohibitive. The telephone interviewer was seated at a computer and read out the questions to the respondent exactly as worded on screen. Additional information was provided on screen for the interviewer to use if the respondent needed it. The interviewer entered the responses directly into the database, a feature that improves data quality. CATI also permits the inclusion of complex skip patterns, allowing inapplicable questions to be automatically skipped and appropriately coded and enabling earlier responses to be used to tailor subsequent questions (e.g. referring to a male partner as ‘him’ rather than ‘your partner’ every time he is mentioned). This saves time and makes the interview less tedious and more like a real conversation because inappropriate questions are not presented to the interviewee. The interviewers for the project were drawn from a pool of experienced telephone interviewers. All interviewers had previously conducted health-related interviews involving sensitive topics and were able to opt out of working on the
Table 1. Components of different interview versions in ASHR2 STI, sexually transmissible infections Component
Demographics Sexual identity/sexual history Heterosexual activity last year Homosexual activity last year Behaviours to increase sexual pleasure Sexual coercion Sexual difficulties last year Condoms, contraception Sex work Health, knowledge and attitudes STI history Blood-borne virus risk Intimate partner violence Internet activity Body modification/surgery A
Respondent characteristicsA One partner in previous year and no same-sex experience Short form Long form
Never had sex
Had sex but not in the last year
* *
* *
* *
* *
* *
*
*
* * * * *
* *
*
* *
* * * * * * * * * * * * * *
More than one partner in the last year or any same-sex experience * * * * * * * * * * * * * * *
If a respondent received a module and the response to the first question indicated that they had no relevant experience (e.g. of sex work or masturbation), no further questions were asked.
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Table 2. Outcome of all telephone calls and calculation of response, cooperation, refusal and contact rates Data show the number of respondents in each category. AAPOR, American Association for Public Opinion Research final disposition codes for random digit dialling (RDD) telephone surveys46 AAPOR codes
Landline Men
Outcome of calls Interview (Category 1) Complete interviews Partial interviews Eligible, non-interview (Category 2) Household-level refusal Selected respondent refusal Break off Non-contact Respondent never available Answering machine household: no message left Answering machine household: message left Physically or mentally unable/incompetent Language problem Unknown eligibility, non-interview (Category 3) Always busy No answer No screener completed Unknown if person is a household resident Not eligible (Category 4) Fax/data line Disconnected number Non-residence No eligible respondent Total phone numbers used Calculation of response rates (AAPOR code) I = Complete interviews (1.1) P = Partial interviews (1.2) R = Refusal and break off (2.1) NC = Non-contact (2.2) O = Other (2.0, 2.3) e = Estimated proportion eligibleA UH = Unknown household (3.1) UO = Unknown other (3.2–3.9) Response rate 1 I/[(I + P) + (R + NC + O) + (UH + UO)] Response rate 2 (I + P)/[(I + P) + (R + NC + O) + (UH + UO)] Response rate 3 I/[(I + P) + (R + NC + O) + e(UH + UO)] Response rate 4 (I + P)/[(I + P) + (R + NC + O) + e(UH + UO)] Cooperation rate 1 I/[(I + P) + R + O] Cooperation rate 2 (I + P)/[(I + P) + R + O] Cooperation rate 3 I/[(I + P) + R] Cooperation rate 4 (I + P)/[(I + P) + R] Refusal rate 1 R/[(I + P) + (R + NC + O) + UH + UO)] Refusal rate 2 R/[(I + P) + (R + NC + O) + e(UH + UO)] Refusal rate 3 R/[(I + P) + (R + NC + O)]
Mobile
Total
Women
1.0/1.1 1.2
4518 7
4599 19
11 010 115
20 127 141
2.111 2.112 2.12 2.20 2.21 2.221 2.222 2.32 2.33
1102 1383 58 812 1856 15 2982 865 506
689 1405 64 319 1047 24 1695 374 461
0 5101 324 48 4869 114 13 812 1068 1101
1791 7889 446 1179 7772 153 18 489 2307 2068
3.12 3.13 3.21 3.30
253 4808 568 260
183 2810 417 281
33 7990 873 1288
469 15 608 1858 1829
4.20 4.32 4.50 4.70
2786 24 679 3805 12 521 63 784
1807 15 972 2407 6338 40 911
17 25 225 3176 5640 81 804
4610 65 876 9388 24 499 186 499
4518 7 2543 5665 1371 0.244 5061 828
4599 19 2158 3085 835 0.287 2993 698
11 010 115 5425 18 843 2169 0.524 8023 2161
20 127 141 10 126 27 593 4375
22.6%
32.0%
23.0%
24.5%
22.6%
32.1%
23.3%
24.7%
29.1%
39.1%
25.6%
28.7%
29.1%
39.3%
25.9%
28.9%
53.5%
60.4%
58.8%
57.9%
53.6%
60.7%
59.4%
58.3%
63.9%
67.9%
66.5%
66.2%
64.0%
68.2%
67.2%
66.7%
12.7%
15.0%
11.4%
12.3%
16.4%
18.4%
12.6%
14.4%
18.0%
20.2%
14.4%
16.2%
16 077 3687
(continued next page)
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Table 2. (continued ) AAPOR codes
Landline Men
Contact rate 1 [(I + P) + R + O]/[(I + P) + R + O + NC + (UH + UO)] Contact rate 2 [(I + P) + R + O]/[(I + P) + R + O + NC + e(UH + UO)] Contact rate 3 [(I + P) + R + O]/[(I + P) + R + O + NC] A
Mobile
Total
Women
42.2%
52.9%
39.2%
42.3%
54.3%
64.7%
43.6%
49.5%
59.8%
71.2%
49.8%
55.8%
The estimated proportion of cases of unknown eligibility that would be eligible if they had been contacted. This estimate is based on the proportion of eligible people among all people or households contacted for whom a definitive determination of status was obtained (a conservative estimate), that is, (Categories 1+2)/(Categories 1+2+4).
study without penalty. Participating interviewers, many of whom had worked on ASHR1, underwent training on sexual issues, as well as on the administration of the questionnaire. The interview schedule was developed to gather information in 16 domains. To facilitate comparison with data from ASHR1, these included: demographics; sexual identity; sexual history; heterosexual activity and condom use in the year before the interview; homosexual activity and condom use in the year before the interview; masturbation and some other solo and partnered sexual practices; sexual coercion; sexual difficulties; contraceptive practices and condom use; sex work; health; STI history; knowledge and attitudes related to sexuality; and bloodborne virus risk behaviours. Additional domains unique to ASHR2 included: intimate partner violence in the year before interview; Internet activity related to sexuality; and body modification and surgery related to sexuality. For most questions, people responded by saying ‘yes’ or ‘no’, or by giving a number, so that anyone who overheard the respondent would not know what they were talking about. If all respondents had been presented with the full interview schedule, most of our resources would have been spent interviewing typical Australians: those in monogamous heterosexual relationships. By restricting the amount of information gathered from people who had had only one sexual partner in the previous year and no homosexual experience, we were able to gather more information from respondents whose behaviour may have put them at higher risk of HIV/STIs and whose other responses (e.g. on attitudes) were more likely to be varied. As shown in Table 1, all respondents provided demographic details and a brief sexual history. From these data, it was possible to identify respondents who reported no partners or more than one partner in the year before being interviewed and those who reported any lifetime same-sex experience. All of these respondents completed a long form of the questionnaire, as did a randomly selected sample of 20% of those reporting one partner in the previous year and no same-sex experience. The remaining 80% of people with one partner in the previous year and no same-sex experience completed a short-form interview. The time saved by this procedure was used to conduct more interviews, enriching the sample by producing a greater number of interviews with people who had engaged in less common and/or more risky behaviours. A similar approach was used in ASHR1 and the French surveys.4,45
The interview duration ranged from 10 to 60 min. The mean interview length was 18.8 min for women interviewed on landlines, 20.0 min for women interviewed on mobiles, 17.8 min for men on landlines and 19.3 for men on mobiles. Pilot study A pilot study was designed to test new questions in ASHR2, test complex skip patterns within the CATI program and provide estimates of the amount of time needed to complete different versions of the survey. In late 2011, pilot interviews were conducted by landline with a random sample of 505 men and 507 women aged 16–69 years in the state of New South Wales. The pilot showed that compared with ASHR1, people aged under 40 years were under-sampled and people over 50 years were over-sampled. This confirmed our decision to conduct the main study with mobile phones as well as landlines. Ethics The study protocol was approved by the Human Ethics Committees of La Trobe University (HEC 11–040) and ratified by the committees at the University of New South Wales, the University of Sydney and the University of Sussex. Sampling and response rates Three sampling frames were used in the study: separate landline sampling frames for men and women, and another sampling frame for those contacted by mobile phone. The number of interviews achieved and the outcomes of calls are presented in Table 2. Of the 20 127 interviews obtained, 33 had missing data, giving a total of 20 094 usable interviews from 9963 men and 10 131 women. Of these, 9106 (45%) were recruited by landline and 10 988 (55%) by mobile phone; among those recruited by mobile phone, 50% were male and 50% female. In cases where interviews were not conducted, the most common reasons were that the telephone number was not allocated or that the household did not contain an eligible person. For landline interviews, where an eligible household was identified and an interview not completed, refusals by the selected participant were slightly more common than household refusals. Landline participation rates among eligible people contacted (i.e. American Association for Public Opinion Research ‘cooperation rate 3’)46 were 63.9%
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Table 3. Comparison of Australian Study of Health and Relationships (ASHR) estimates with Australian Bureau of Statistics estimates *P < 0.01, **P < 0.05 compared with Australian Bureau of Statistics (ABS) estimates, using an exact binomial test against a known proportion Estimate
StateA New South Wales Victoria Queensland Western Australia South Australia Australian Capital Territory Tasmania Northern Territory SexA Males Females Age groupA (years) 16–19 20–24 25–29 30–34 35–39 40–44 45–49 50–54 55–59 60–65 65–69 Legal marital statusB Married (excluding de-facto) Divorced Separated Widowed Never married BirthplaceC Australia Outside Australia Main English-speaking countries Other countries Indigenous statusB Indigenous Non-indigenous Labour force statusD Employed Full-time Part-time Unemployed Not in the labour force Educational attainmentE Postgraduate degreeF Undergraduate degreeF College certificate or diplomaF Higher secondary schoolF Technical or trade certificateF Lower secondary school or lowerF Level not determined Managers Professionals Other
ABS (%)
Items asked of all respondents Unweighted Design Final (%) weights (%) weights (%)
Unweighted (%)
Long-form items Design weights (%)
Final weights (%)
31.9 24.9 20.1 10.9 7.2 1.7 2.2 1.1
31.8 24.5 19.7 10.5 7.5 2.1** 3.3** 0.6**
31.2*A 23.9** 20.4 10.7 7.6* 2.1** 3.4** 0.8**
31.9 24.9 20.1 10.9 7.2 1.7 2.2 1.1
31.9 24.6 20.1 9.9** 7.4 2.3** 3.2** 0.6**
31.8 23.8** 20.6 10.1** 7.3 2.1** 3.4** 0.8**
31.9 24.9 20.1 10.9 7.2 1.7 2.2 1.1
50.0 50.0
49.6 50.4
50.3 49.8
50.0 50.0
47.3** 52.7**
49.7 50.3
50.0 50.0
7.4 10.2 10.6 10.0 9.8 10.3 9.6 9.6 8.6 7.7 6.4
4.1** 5.2** 6.2** 7.8** 9.2** 10.9** 10.9** 12.5** 12.6** 11.4** 9.1**
4.4** 6.7** 8.1** 8.9** 9.3** 10.4 10.3** 11.8** 11.6** 10.5** 8.1**
7.4 10.2 10.5 10.0 9.8 10.2 9.6 9.6 8.6 7.6 6.5
7.1 7.6** 6.5** 6.8** 7.8** 9.2** 9.1* 11.2** 12.2** 11.9** 10.6**
4.6** 7.2** 7.5** 8.7** 9.4 11.4** 9.6 11.7** 11.3** 10.3** 8.2**
7.4 10.4 10.5 9.9 9.8 10.2 9.6 9.6 8.5 7.7 6.5
49.0 8.6 3.3 1.7 37.3
59.6** 9.9** 3.4 1.9* 25.1**
53.9** 10.3** 3.9** 1.9* 29.9**
51.6** 7.9** 3.0* 1.4** 36.1**
40.5** 14.5** 5.2** 3.6** 36.1**
53.9** 10.0** 3.9** 1.9* 30.3**
51.4** 7.9** 2.9** 1.4** 36.4*
69.1 30.9 10.6 20.3
76.8** 23.2** 11.5** 11.8**
76.9** 23.1** 11.2* 11.9**
76.5** 23.5** 10.5 13.0**
78.0** 22.0** 11.3** 10.7**
77.4** 22.6** 11.2** 11.4**
76.6** 23.4** 10.6 12.7**
2.3 97.7
1.7** 98.3**
2.1 97.9
2.0** 98.0**
1.9** 98.1**
2.2 97.8
2.1* 97.9*
72.2 51.3 20.9 4.0 23.7
72.7 49.9** 22.9** 2.7** 24.6**
72.7 50.4* 22.3** 3.1** 24.1
73.3** 50.0** 23.3** 3.3** 23.4
68.6** 44.7** 23.8** 3.5** 27.8**
72.8 49.7** 23.1** 3.3** 23.9
72.9* 49.1** 23.8** 3.8 23.3
7.4 18.0 10.0 27.1 17.5 19.9 0.1
15.6** 17.7 20.3** 15.4** 13.4** 17.4** 0.1
15.1** 17.9 20.0** 15.9** 13.6** 17.4** 0.1
15.1** 18.9** 19.4** 18.0** 12.5** 16.0** 0.1
14.0** 17.4* 20.** 17.3** 11.9** 19.3* 0.1
14.3** 17.1** 20.6** 16.5** 13.5** 17.8** 0.1
14.7** 18.0 20.2** 18.3** 12.4** 16.4** 0.1
Occupation category (employed people)G 17.1** 16.2** 15.2** 24.3** 23.8** 23.9** 58.6** 60.** 61.0**
14.7** 22.6 62.6**
15.5** 23.0 61.4**
14.2** 22.7 60.8**
12.7 22.2 65.1
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Table 3. (continued ) Estimate
Relationship in householdC Lone person Smoking statusH Never smoked Past smoker Current smoker Average absolute differenceI
ABS (%)
Items asked of all respondents Unweighted Design Final (%) weights (%) weights (%)
Unweighted (%)
Long-form items Design weights (%)
Final weights (%)
8.9
10.3**
12.4**
9.5**
18.0**
11.7**
9.3**
53.7 26.9 19.4
48.9** 31.5** 19.5 2.9
48.0** 30.2** 21.7** 2.5
52.8* 26.5 20.6** 1.5
48.9** 31.5** 19.5 3.2
50.3** 31.7** 18.0** 2.5
53.7 28.6** 17.6** 1.5
The ABS estimates for state, sex and age group were the final estimated residential population as at 30 June 2012 (see http://www.abs.gov.au).59 The ABS figures for marital status, indigenous status and lone households were obtained from the 2011 Census of Population and Housing. The figures relate to individuals aged 16 to 69 years and include people in non-private dwellings (see http://www.abs.gov.au). C These estimates relate to individuals aged at least 15 years. The main English-speaking countries category includes the UK, Ireland, South Africa, Canada, the US and New Zealand.60 D Labour Force Survey estimates for December 2012.61 These estimates relate to individuals aged 15 to 64 years. E These estimates relate to individuals aged 15 to 64 years and exclude people in remote parts of Australia and people in most non-private dwellings (but includes those in boarding schools).62 F Postgraduate degrees include graduate diplomas and graduate certificates. Undergraduate degrees refer to bachelor degrees. A college certificate or diploma refers to advanced diplomas or diplomas. Higher secondary school refers to Years 11 and 12, lower secondary school refers to Year 10. Technical trade certificates refers to Certificates I, II, III or IV. G The ABS estimates come from the Labour Force Survey August 2012.63 ASHR2 uses Australian Standard Classification of Occupations (ASCO) coding64 to match ASHR1, whereas the Labour Force Survey data is coded using the new Australian and New Zealand Standard Classification of Occupations (ANZSCO) system.65 These coding systems are considered sufficiently compatible for valid comparisons of managers and professionals to be made. H ABS estimates for smoking status were obtained from the 2011–12 Australian health survey.66 These estimates relate to individuals aged 15 to 64 years. I Mean of absolute differences between estimates and the ABS benchmarks for the column. A
B
for men and 67.9% for women. Within the mobile phone sample, the participation rate was 66.5%. The overall participation rate was 66.2%. Weighting A two-stage approach was used to weight the data. First, design weights were calculated to adjust for: the probability of each respondent being selected for a landline interview, given the number of landline interviews achieved in relation to the estimated number of residential landlines in Australia as well as the number of landlines and in-scope adults in respondents’ households; the probability of being selected for a mobile phone interview, given the number of mobile phone interviews achieved in relation to the estimated number of mobile phones in Australia; the overlapping chances of selection for persons with both a mobile phone and a landline; and the reduced probability that persons with one partner in the previous year and no homosexual experience would be given the long-form interview. After taking into account the design weights for the study, the sample still demonstrated some deviation from the Australian population in relation to its age–sex distribution and locality. Accordingly, the data were then weighted to match the Australian population on the basis of age, sex, area of residence (i.e. state by Accessibility/Remoteness Index of Australia (ARIA) category of urban, regional or remote47) and telephone ownership (i.e. mobile telephone only vs other), using population benchmarks provided by the Australian Bureau of Statistics (Table 3). This resulted in a weighted sample of 20 094 people (10 056 men and 10 038 women).
For questions asked of all respondents, final weights were constrained to be between 0.2 and 5, with a mean of 1. For questions asked only in long-form interviews, no constraints were used and the final weights ranged from 0.15 to 28.4, with a mean of 2.34. All analyses use these final weights, using the survey estimation commands in Stata Version 11.2.48 The design effects were 1.366 for men and 1.343 for women, giving effective sample sizes of 7294 men and 7542 women, and a total of 14 836. As can be seen, after adjusting for location, age and sex, the sample was consistent with the 2011 Census with regard to these variables. The sample appears to slightly overrepresent married people, although it is possible that this reflects respondents describing themselves as married while actually living in what is legally a de facto relationship. Given that the interviews were only conducted in English, it is not surprising that overseas-born people from nonEnglish-speaking countries are under-represented. Australia has no single large language group whose members have a high proportion of non-English speakers (like Spanish speakers in the USA), and it would have been prohibitively expensive to translate and program foreign-language interviews and to train interviewers for other languages. People who were in part-time employment were somewhat over-represented and people in full-time employment were somewhat under-represented, presumably because the latter were busy and harder to reach. Those in managerial occupations were over-represented and those with lower levels of education and smokers were under-represented. Given the correlation between these three variables, this seems likely to represent a single form of bias.
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Table 4. Sociodemographic profile of the sample: weighted frequencies (and column percentages) Data show the number of individuals in each group, with percentages in parentheses
Age (years) 16–19 20–29 30–39 40–49 50–59 60–69 Language spoken at home English Other Missing Education Less than secondary Secondary Post-secondary Don’t know/Can’t remember Refused Region Major city Regional Remote Don’t knowB RefusedB MissingB Household income $28 000 $28 001–$52 000 $52 001–$83 000 $83 001–$125 000 > $125 000 Refused Missing Occupation Blue collar White collar Manager/professional Never worked Refused
Men (n = 10 056)
Women (n = 10 038)
778 2060 1899 1917 1852 1551
713 2105 2072 2056 1806 1286
(7.7) (20.5) (18.9) (19.1) (18.4) (15.4)
(7.1) (21.0) (20.6) (20.5) (18.0) (12.8)
TotalA (n = 20 094) 1491 4165 3971 3973 3658 2836
(7.4) (20.7) (19.8) (19.8) (18.2) (14.1)
9217 (91.7) 838 (8.3) 2 (0.0)
9353 (93.2) 685 (6.8) 0
18 570 (92.4) 1523 (7.6) 2 (0.0)
1513 3688 4845 4 7
(15.0) (36.7) (48.2) (0.0) (0.1)
1702 2437 5891 2 6
(17.0) (24.3) (58.7) (0.0) (0.1)
3215 6125 10 736 6 13
(16.0) (30.5) (53.4) (0.0) (0.1)
6837 2775 245 66 37 96
(68.0) (27.6) (2.4) (0.7) (0.4) (1.0)
6904 2780 202 39 42 71
(68.8) (27.7) (2.0) (0.4) (0.4) (0.7)
13 741 5554 447 106 78 167
(68.4) (27.6) (2.2) (0.5) (0.4) (0.8)
1274 1356 1973 2014 2768 671 2
(12.7) (13.5) (19.6) (20.0) (27.5) (6.7) (0.0)
1593 (15.9) 1523 (15.2) 1948 (19.4) 1949 (19.4) 2124 (21.2) 901 (9.0) 0
2866 2879 3921 3963 4892 1572 2
(14.3) (14.3) (19.5) (19.7) (24.3) (7.8) (0.0)
3533 2316 3992 153 62
(35.1) (23.0) (39.7) (1.5) (0.6)
1111 5016 3683 161 67
4644 7332 7675 314 130
(23.1) (36.5) (38.2) (1.6) (0.6)
(11.1) (50.0) (36.7) (1.6) (0.7)
A
Frequency totals may differ by one due to rounding. Postcode or location data missing for allocation to ARIA region.
B
Table 4 presents the main sociodemographic factors used as correlates of sexual behaviours in many of the accompanying papers, allowing readers to see what proportion of the sample belonged to each group. Respondent embarrassment and honesty As shown in Table 5, 90% of the respondents were either ‘not at all’ embarrassed by the questionnaire or ‘slightly’ embarrassed (Box 1). Furthermore, 89% of respondents reported having been ‘entirely honest’ in their responses to questions, with another 10% being honest at least 90% of the time (Table 6; Box 1). c2 tests were used to check for significant correlates of embarrassment and honesty shown in Tables 5 and 6. Women (12.6%) were more likely to report more than slight embarrassment than men (7.2%; P < 0.001). Higher levels of
embarrassment were reported by people who were: younger (P < 0.001), did not speak English at home (P < 0.001), had completed post-secondary education (P < 0.001), lived in major cities or remote areas (P < 0.001), had low incomes (P < 0.001), or had white-collar or managerial occupations (P < 0.001). The likelihood of being less than 90% honest in responding to the survey was significantly greater among men who did not speak English at home (P = 0.006) or had very low incomes (P < 0.001). The likelihood of being less than 90% honest in responding to the survey was significantly greater among women who did not speak English at home (P < 0.001) or lived in major cities (P = 0.02). Presentation of statistics Most percentages are given in the papers in this issue without standard errors or 95% confidence intervals. This decision was
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Table 5.
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Sociodemographic correlates of the degree of embarrassment reported in completing the interview
Correlate
Degree of embarrassment Quite, very or extremely embarrassing (%)
Overall Age (years) 16–19 20–29 30–39 40–49 50–59 60–69 Language spoken at home English Other Education Less than secondary Secondary Post-secondary Region of residence Major city Regional Remote Household income group $28 000 $28 001–$52 000 $52 001–$83 000 $83 001–$125 000 > $125 000 Occupational category Blue collar White collar Manager/professional
Men (n = 10 043) Slightly embarrassing (%)
Not at all embarrassing (%)
Quite, very or extremely embarassing (%)
Women (n = 10 025) Slightly embarrassing (%)
Not at all embarrassing (%)
7.2
27.9
64.9
12.6
34.9
52.4
9.1 9.1 7.7 7.0 5.5 5.2
33.3 30.2 28.7 28.9 26.8 21.1
57.6 60.7 63.6 64.1 67.6 73.7
13.1 15.6 14.7 12.5 10.4 7.8
35.4 38.8 37.8 36.8 32.6 24.1
51.6 45.7 47.5 50.7 57.1 68.2
6.3 16.7
28.1 25.6
65.6 57.7
11.8 24.5
35.1 32.2
53.1 43.3
5.9 6.9 7.7
24.9 24.5 31.4
69.2 68.5 60.9
9.8 11.7 13.8
30.1 35.5 36.1
60.2 52.8 50.1
7.7 5.4 8.4
29.1 25.1 24.8
63.1 69.5 66.8
13.4 10.5 11.3
35.7 32.9 37.1
50.9 56.7 51.6
9.2 6.9 6.7 6.1 6.1
25.4 25.6 27.3 29.5 28.4
65.4 67.5 66.0 64.3 65.5
14.0 10.1 12.4 10.8 12.6
31.0 32.0 35.5 39.2 36.3
55.0 57.9 52.1 50.0 51.1
6.2 7.9 7.4
23.8 29.6 29.7
70.0 62.5 62.9
10.7 12.6 12.9
30.4 35.5 35.7
58.9 51.9 51.4
Box 1.
Ascertainment of embarrassment and honesty
That’s the end of the study questions, but I’d also like to ask some quick questions about the questionnaire. How embarrassing did you find the questionnaire? *
Extremely embarrassing
*
Very embarrassing
*
Quite embarrassing
*
Slightly embarrassing
*
Not at all embarrassing
In percentage terms, how honest were you in your answers to the questionnaire?
made to maximise both readability and brevity and is consistent with the style of reporting of studies of similar scope and intent.1,3,49 Figure 1 displays approximate standard errors for observed percentages in subsamples of different sizes, both for questions asked of all participants and for those in the long-form survey
only (marked L). As can be seen, when the entire sample is employed for questions asked of everyone, the standard error remains below 0.5 percentage points. Thus, using a normal approximation, the 95% confidence interval for any estimate involving the entire sample will be less than 1 percentage points. Similarly, when approximately half the sample is used, or
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Table 6. Sociodemographic correlates of the degree of honesty reported in relation to answers given during the interview Correlate
Overall Age (years) 16–19 20–29 30–39 40–49 50–59 60–69 Language spoken at home English Other Education Less than secondary Secondary Post-secondary Region of residence Major city Regional Remote Household income group $28 000 $28 001–$52 000 $52 001–$83 000 $83 001–$125 000 > $125 000 Occupational category Blue collar White collar Manager/professional
Sexual Health, 2014, 11, 383–396 http://dx.doi.org/10.1071/SH14115
Design and methods of the Second Australian Study of Health and Relationships Juliet Richters A,J, Paul B. Badcock B,C, Judy M. Simpson D, David Shellard E, Chris RisselF, Richard O. de VisserG, Andrew E. GrulichH and Anthony M. A. Smith B,I A
School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW 2052, Australia. B Australian Research Centre in Sex, Health and Society, La Trobe University, 215 Franklin Street, Melbourne, Vic. 3000, Australia. C Centre for Youth Mental Health, University of Melbourne, Orygen Youth Health Research Centre, 35 Poplar Road, Parkville, Vic. 3052, Australia. D Sydney School of Public Health, Edward Ford Building (A27), University of Sydney, Sydney, NSW 2006, Australia. E Hunter Valley Research Foundation, PO Box 322, Newcastle, NSW 2300, Australia. F Sydney School of Public Health, Charles Perkins Centre (D17), University of Sydney, Sydney, NSW 2006, Australia. G School of Psychology, Pevensey 1, University of Sussex, Falmer BN1 9QH, UK. H The Kirby Institute, Wallace Wurth Building, University of New South Wales, Sydney, NSW 2052, Australia. I Deceased. J Corresponding author. Email: [email protected]
Abstract. Background: This paper describes the methods and process of the Second Australian Study of Health and Relationships. Methods: A representative sample of the Australian population was contacted by landline and mobile phone modified random-digit dialling in 2012–13. Computer-assisted telephone interviews elicited sociodemographic and health details as well as sexual behaviour and attitudes. For analysis, the sample was weighted to reflect the study design and further weighted to reflect the location, age and sex distribution of the population at the 2011 Census. Results: Interviews were completed with 9963 men and 10 131 women aged 16–69 years from all states and territories. The overall participation rate among eligible people was 66.2% (63.9% for landline men, 67.9% for landline women and 66.5% for mobile respondents). Accounting for the survey design and adjusting to match the 2011 Census resulted in a weighted sample of 20 094 people (10 056 men and 10 038 women). The sample was broadly representative of the Australian population, although as in most surveys, people with higher education and higher status occupations were overrepresented. Data quality was high, with the great majority saying they were not at all or only slightly embarrassed by the questionnaire and almost all saying they were 90–100% honest in their answers. Conclusions: The combination of methods and design in the Second Australian Study of Health and Relationships, together with the high participation rate, strongly suggests that the results of the study are robust and broadly representative of the Australian population. Additional keywords: methodology, national survey, random sampling, sexual behavior, telephone survey. Received 16 June 2014, accepted 3 September 2014, published online 7 November 2014
Introduction The first Australian Study of Health and Relationships (ASHR1) was the largest and most comprehensive population-based survey of sexuality ever undertaken in Australia and one of the largest in the world.1 Conducted in 2001–02, it emerged from a context of increasing interest in people’s sexual behaviour throughout the world, motivated largely by the rise and spread of the global HIV/AIDS epidemic in the 1980s and Journal compilation CSIRO 2014
1990s. Beyond HIV risk, the scholarly interest in sexual behaviour now includes sexual experiences and lifestyles. Overseas studies, most notably the British,2 American3 and French4 national surveys, combined sociological, sexological and epidemiological expertise to provide nationwide representative data. The need for an Australian national sex survey had been recognised by social and behavioural scientists, public health www.publish.csiro.au/journals/sh
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researchers and health policy planners in the 1990s. In response to this need, and drawing on the work done by the British,2 Americans3 and French,4 ASHR1 aimed to: provide a representative national population-based prevalence study of the sexual health and practices of Australian adults; identify the frequency and extent of sexually transmissible infection (STI) and HIV risk practices and the social, demographic and behavioural characteristics associated with such practices; and identify attitudes and current levels of knowledge regarding STIs and HIV/AIDS.1 The findings have been used widely in health policy and health promotion, research and clinical care. At the same time, a smaller representative sample survey, using similar methods,5 produced results broadly similar to those of ASHR1.6–8 Before ASHR1, apart from clinical studies, behavioural sex research in Australia consisted mostly of convenience-sample surveys of at-risk groups such as gay and other homosexually active men,9–14 lesbian, bisexual and other women in contact with the gay community,15 transgender people,16 sex workers17 and sexual health clinic clients, as well as groups of ongoing concern such as young people.18 This approach had served well to support community-based HIV-prevention programs, especially among gay men. However, the degree to which these studies validly represented the groups they surveyed was unknown. For example, were the capital-city periodic surveys of homosexually active men representative of such men in general, or skewed towards the more community-attached gay men? Comparing such groups with the gay-identified and homosexually active men in ASHR1 allowed researchers to assess the representativeness of convenience samples and thus increase their value for planning campaigns and predicting health service needs and infection risks at a population level.19 Probability sampling had been used before ASHR1 to survey secondary school20 and technical college students.21 During the 2000s, several sexual health surveys of the Australian population were carried out, such as the Australian Longitudinal Study of Health and Relationships,22 a smaller cohort study focusing on people in regular relationships. Further nationally representative surveys of secondary school students also took place.23,24 Other population-based studies such as the Household, Income and Labour Dynamics in Australia survey (www.melbourneinstitute. com/hilda, accessed 15 September 2014) also collect some information relevant to reproductive and sexual health, as does the Australian Longitudinal Study on Women’s Health (www.alswh.org.au, accessed 15 September 2015).25,26 The aims of the Second Australian Study of Health and Relationships (ASHR2) were to build on this body of knowledge by: (1) providing a representative national population-based study of the sexual and reproductive health of Australian adults aged 16–69 years; (2) describing changes in the sexual and reproductive health of Australian adults aged 16–59 years between 2001–02 and 2012–13 by comparing the ASHR1 data with current patterns; and (3) providing the first large-scale national data addressing the sexual health of Australian men and women aged 60–69 years. The decision to extend the age range of respondents to include people aged 60–69 years was based on the lack of information on the sexual health and behaviour of older groups27 and to enable us to compare them with those aged 50–59 years
J. Richters et al.
in ASHR1. Although Australia’s ageing population makes the sexual health of older people a mainstream issue for policy and practice, we did not attempt to include people over 70 years, as this would have required major changes in the questionnaire and in the recruitment methods to include those not living in households (e.g.those in aged care institutions). Methodology of ASHR2 Sampling We used dual-frame modified random-digit dialling (RDD) to recruit a sample for interview, combining traditional directoryassisted landline-based RDD with RDD of mobile telephones. Although there is continuing debate about the relative merits of RDD and sampling from directories,28,29 relying on directories alone precludes sampling of the mobile-only population and households with silent or unlisted numbers. The use of both a landline and mobile phone sampling frame was motivated by recent changes in Australian telecommunication patterns. At the time of ASHR1, over 97% of Australian households had a landline telephone.30 Recently, however, the representativeness of landline surveys has been challenged by the rise of mobile phone use and the decline in the proportion of households with fixed telephone lines that are used for incoming calls.31,32 Although not as high as the US figure of 34%,33 an Australian estimate from the time of ASHR2 indicated that in 2012, approximately 20% of adults lived in households without a fixed line telephone.34 The inability of landline-based surveys to reach such a substantial proportion of the population introduces an important bias.35–37 A further complication arises from the usage patterns of those who have access to both landlines and mobile phones,35 with non-response bias likely to be further exacerbated by landline householders who rely chiefly on their mobile for communication.38 Mobile-only users differ from those with landlines in demographic characteristics, attitudes and healthrelated behaviours.32,33,35,39–41 The modified RDD used for this study was as follows. Two landline samples and one mobile sample were randomly extracted from the electronic White Pages. Subsequently, the samples were modified by adding a small, randomly generated value to the telephone number, a method which produces a set of numbers that quite closely maps the Australian population. The final sample of numbers was compared with listed business numbers and any matches were deleted. Although this was more efficient than simple RDD, we still had to generate 185 600 different telephone numbers in order to obtain 20 127 interviews. Each randomly generated landline telephone number was linked to the electronic White Pages telephone directory and when a match was identified, an adjacent number was extracted with its corresponding household address. Households were then notified by letter that their number had been generated and that they would receive a telephone call. Addresses were identified for 36.6% of the landline telephone numbers generated by the RDD procedure. Using letters to forewarn households of an impending telephone call improves response rates,42,43 partly by increasing the perceived legitimacy of the survey. The letter explained the purpose and nature of the study, together with
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the names of the universities involved and the contact details for the lead researcher and the relevant ethics committee secretariat for further information. After a prospective respondent was selected, the interviewer explained the study, stressing that it was anonymous and voluntary and that the respondent could decline to answer any questions if s/he wished. Consent was obtained verbally with the questions ‘Do I have your consent to proceed? Is it OK to talk to you now?’. Up to six initial contact calls were made to each mobile and landline number. If any contact was made with a landline, a further five calls were made. For mobiles, at least five calls were made; 5% of mobile interviews required more than 10 calls to complete. When a selected telephone number was answered, the interviewer introduced the study. Calls to landlines were introduced as either the ‘Australian Study of Men’s Health and Relationships’ or ‘. . . Women’s Health and Relationships’, as this single-sex mode of recruitment has been found to elicit higher response rates. The person answering the landline was asked how many men (or women) between the ages of 16 and 69 years lived in the household. If there was more than one eligible resident, the computer-assisted telephone interview (CATI) program randomly selected the interviewee using an age-order protocol to prevent respondents self-selecting. When a mobile phone was answered, it was assumed to be the speaker’s own phone and the male or female questionnaire was selected. Respondents who requested more information about the study than was presented in the introduction could have it read to them or they could receive a letter via email, fax or mail, or they could consult the website; the last option was the most common way that respondents validated the study. Female interviewers employed by the Hunter Valley Research Foundation conducted all interviews. A male
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interviewer was available but never requested. All interviews were conducted in English. The interviews We chose telephone interviews rather than face-to-face interviews for ASHR1 because they allow greater privacy, do not require high levels of literacy and provide an efficient method that allows for quality control throughout the entire process of data collection.1,42,44 The potential for interviewer bias is also lower in telephone interviews because of the lack of face-to-face contact and the inability of participants to respond to non-verbal cues from interviewers.1,44 Finally, the low population density in Australia rendered the cost of face-toface interviews prohibitive. The telephone interviewer was seated at a computer and read out the questions to the respondent exactly as worded on screen. Additional information was provided on screen for the interviewer to use if the respondent needed it. The interviewer entered the responses directly into the database, a feature that improves data quality. CATI also permits the inclusion of complex skip patterns, allowing inapplicable questions to be automatically skipped and appropriately coded and enabling earlier responses to be used to tailor subsequent questions (e.g. referring to a male partner as ‘him’ rather than ‘your partner’ every time he is mentioned). This saves time and makes the interview less tedious and more like a real conversation because inappropriate questions are not presented to the interviewee. The interviewers for the project were drawn from a pool of experienced telephone interviewers. All interviewers had previously conducted health-related interviews involving sensitive topics and were able to opt out of working on the
Table 1. Components of different interview versions in ASHR2 STI, sexually transmissible infections Component
Demographics Sexual identity/sexual history Heterosexual activity last year Homosexual activity last year Behaviours to increase sexual pleasure Sexual coercion Sexual difficulties last year Condoms, contraception Sex work Health, knowledge and attitudes STI history Blood-borne virus risk Intimate partner violence Internet activity Body modification/surgery A
Respondent characteristicsA One partner in previous year and no same-sex experience Short form Long form
Never had sex
Had sex but not in the last year
* *
* *
* *
* *
* *
*
*
* * * * *
* *
*
* *
* * * * * * * * * * * * * *
More than one partner in the last year or any same-sex experience * * * * * * * * * * * * * * *
If a respondent received a module and the response to the first question indicated that they had no relevant experience (e.g. of sex work or masturbation), no further questions were asked.
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Table 2. Outcome of all telephone calls and calculation of response, cooperation, refusal and contact rates Data show the number of respondents in each category. AAPOR, American Association for Public Opinion Research final disposition codes for random digit dialling (RDD) telephone surveys46 AAPOR codes
Landline Men
Outcome of calls Interview (Category 1) Complete interviews Partial interviews Eligible, non-interview (Category 2) Household-level refusal Selected respondent refusal Break off Non-contact Respondent never available Answering machine household: no message left Answering machine household: message left Physically or mentally unable/incompetent Language problem Unknown eligibility, non-interview (Category 3) Always busy No answer No screener completed Unknown if person is a household resident Not eligible (Category 4) Fax/data line Disconnected number Non-residence No eligible respondent Total phone numbers used Calculation of response rates (AAPOR code) I = Complete interviews (1.1) P = Partial interviews (1.2) R = Refusal and break off (2.1) NC = Non-contact (2.2) O = Other (2.0, 2.3) e = Estimated proportion eligibleA UH = Unknown household (3.1) UO = Unknown other (3.2–3.9) Response rate 1 I/[(I + P) + (R + NC + O) + (UH + UO)] Response rate 2 (I + P)/[(I + P) + (R + NC + O) + (UH + UO)] Response rate 3 I/[(I + P) + (R + NC + O) + e(UH + UO)] Response rate 4 (I + P)/[(I + P) + (R + NC + O) + e(UH + UO)] Cooperation rate 1 I/[(I + P) + R + O] Cooperation rate 2 (I + P)/[(I + P) + R + O] Cooperation rate 3 I/[(I + P) + R] Cooperation rate 4 (I + P)/[(I + P) + R] Refusal rate 1 R/[(I + P) + (R + NC + O) + UH + UO)] Refusal rate 2 R/[(I + P) + (R + NC + O) + e(UH + UO)] Refusal rate 3 R/[(I + P) + (R + NC + O)]
Mobile
Total
Women
1.0/1.1 1.2
4518 7
4599 19
11 010 115
20 127 141
2.111 2.112 2.12 2.20 2.21 2.221 2.222 2.32 2.33
1102 1383 58 812 1856 15 2982 865 506
689 1405 64 319 1047 24 1695 374 461
0 5101 324 48 4869 114 13 812 1068 1101
1791 7889 446 1179 7772 153 18 489 2307 2068
3.12 3.13 3.21 3.30
253 4808 568 260
183 2810 417 281
33 7990 873 1288
469 15 608 1858 1829
4.20 4.32 4.50 4.70
2786 24 679 3805 12 521 63 784
1807 15 972 2407 6338 40 911
17 25 225 3176 5640 81 804
4610 65 876 9388 24 499 186 499
4518 7 2543 5665 1371 0.244 5061 828
4599 19 2158 3085 835 0.287 2993 698
11 010 115 5425 18 843 2169 0.524 8023 2161
20 127 141 10 126 27 593 4375
22.6%
32.0%
23.0%
24.5%
22.6%
32.1%
23.3%
24.7%
29.1%
39.1%
25.6%
28.7%
29.1%
39.3%
25.9%
28.9%
53.5%
60.4%
58.8%
57.9%
53.6%
60.7%
59.4%
58.3%
63.9%
67.9%
66.5%
66.2%
64.0%
68.2%
67.2%
66.7%
12.7%
15.0%
11.4%
12.3%
16.4%
18.4%
12.6%
14.4%
18.0%
20.2%
14.4%
16.2%
16 077 3687
(continued next page)
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Table 2. (continued ) AAPOR codes
Landline Men
Contact rate 1 [(I + P) + R + O]/[(I + P) + R + O + NC + (UH + UO)] Contact rate 2 [(I + P) + R + O]/[(I + P) + R + O + NC + e(UH + UO)] Contact rate 3 [(I + P) + R + O]/[(I + P) + R + O + NC] A
Mobile
Total
Women
42.2%
52.9%
39.2%
42.3%
54.3%
64.7%
43.6%
49.5%
59.8%
71.2%
49.8%
55.8%
The estimated proportion of cases of unknown eligibility that would be eligible if they had been contacted. This estimate is based on the proportion of eligible people among all people or households contacted for whom a definitive determination of status was obtained (a conservative estimate), that is, (Categories 1+2)/(Categories 1+2+4).
study without penalty. Participating interviewers, many of whom had worked on ASHR1, underwent training on sexual issues, as well as on the administration of the questionnaire. The interview schedule was developed to gather information in 16 domains. To facilitate comparison with data from ASHR1, these included: demographics; sexual identity; sexual history; heterosexual activity and condom use in the year before the interview; homosexual activity and condom use in the year before the interview; masturbation and some other solo and partnered sexual practices; sexual coercion; sexual difficulties; contraceptive practices and condom use; sex work; health; STI history; knowledge and attitudes related to sexuality; and bloodborne virus risk behaviours. Additional domains unique to ASHR2 included: intimate partner violence in the year before interview; Internet activity related to sexuality; and body modification and surgery related to sexuality. For most questions, people responded by saying ‘yes’ or ‘no’, or by giving a number, so that anyone who overheard the respondent would not know what they were talking about. If all respondents had been presented with the full interview schedule, most of our resources would have been spent interviewing typical Australians: those in monogamous heterosexual relationships. By restricting the amount of information gathered from people who had had only one sexual partner in the previous year and no homosexual experience, we were able to gather more information from respondents whose behaviour may have put them at higher risk of HIV/STIs and whose other responses (e.g. on attitudes) were more likely to be varied. As shown in Table 1, all respondents provided demographic details and a brief sexual history. From these data, it was possible to identify respondents who reported no partners or more than one partner in the year before being interviewed and those who reported any lifetime same-sex experience. All of these respondents completed a long form of the questionnaire, as did a randomly selected sample of 20% of those reporting one partner in the previous year and no same-sex experience. The remaining 80% of people with one partner in the previous year and no same-sex experience completed a short-form interview. The time saved by this procedure was used to conduct more interviews, enriching the sample by producing a greater number of interviews with people who had engaged in less common and/or more risky behaviours. A similar approach was used in ASHR1 and the French surveys.4,45
The interview duration ranged from 10 to 60 min. The mean interview length was 18.8 min for women interviewed on landlines, 20.0 min for women interviewed on mobiles, 17.8 min for men on landlines and 19.3 for men on mobiles. Pilot study A pilot study was designed to test new questions in ASHR2, test complex skip patterns within the CATI program and provide estimates of the amount of time needed to complete different versions of the survey. In late 2011, pilot interviews were conducted by landline with a random sample of 505 men and 507 women aged 16–69 years in the state of New South Wales. The pilot showed that compared with ASHR1, people aged under 40 years were under-sampled and people over 50 years were over-sampled. This confirmed our decision to conduct the main study with mobile phones as well as landlines. Ethics The study protocol was approved by the Human Ethics Committees of La Trobe University (HEC 11–040) and ratified by the committees at the University of New South Wales, the University of Sydney and the University of Sussex. Sampling and response rates Three sampling frames were used in the study: separate landline sampling frames for men and women, and another sampling frame for those contacted by mobile phone. The number of interviews achieved and the outcomes of calls are presented in Table 2. Of the 20 127 interviews obtained, 33 had missing data, giving a total of 20 094 usable interviews from 9963 men and 10 131 women. Of these, 9106 (45%) were recruited by landline and 10 988 (55%) by mobile phone; among those recruited by mobile phone, 50% were male and 50% female. In cases where interviews were not conducted, the most common reasons were that the telephone number was not allocated or that the household did not contain an eligible person. For landline interviews, where an eligible household was identified and an interview not completed, refusals by the selected participant were slightly more common than household refusals. Landline participation rates among eligible people contacted (i.e. American Association for Public Opinion Research ‘cooperation rate 3’)46 were 63.9%
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Table 3. Comparison of Australian Study of Health and Relationships (ASHR) estimates with Australian Bureau of Statistics estimates *P < 0.01, **P < 0.05 compared with Australian Bureau of Statistics (ABS) estimates, using an exact binomial test against a known proportion Estimate
StateA New South Wales Victoria Queensland Western Australia South Australia Australian Capital Territory Tasmania Northern Territory SexA Males Females Age groupA (years) 16–19 20–24 25–29 30–34 35–39 40–44 45–49 50–54 55–59 60–65 65–69 Legal marital statusB Married (excluding de-facto) Divorced Separated Widowed Never married BirthplaceC Australia Outside Australia Main English-speaking countries Other countries Indigenous statusB Indigenous Non-indigenous Labour force statusD Employed Full-time Part-time Unemployed Not in the labour force Educational attainmentE Postgraduate degreeF Undergraduate degreeF College certificate or diplomaF Higher secondary schoolF Technical or trade certificateF Lower secondary school or lowerF Level not determined Managers Professionals Other
ABS (%)
Items asked of all respondents Unweighted Design Final (%) weights (%) weights (%)
Unweighted (%)
Long-form items Design weights (%)
Final weights (%)
31.9 24.9 20.1 10.9 7.2 1.7 2.2 1.1
31.8 24.5 19.7 10.5 7.5 2.1** 3.3** 0.6**
31.2*A 23.9** 20.4 10.7 7.6* 2.1** 3.4** 0.8**
31.9 24.9 20.1 10.9 7.2 1.7 2.2 1.1
31.9 24.6 20.1 9.9** 7.4 2.3** 3.2** 0.6**
31.8 23.8** 20.6 10.1** 7.3 2.1** 3.4** 0.8**
31.9 24.9 20.1 10.9 7.2 1.7 2.2 1.1
50.0 50.0
49.6 50.4
50.3 49.8
50.0 50.0
47.3** 52.7**
49.7 50.3
50.0 50.0
7.4 10.2 10.6 10.0 9.8 10.3 9.6 9.6 8.6 7.7 6.4
4.1** 5.2** 6.2** 7.8** 9.2** 10.9** 10.9** 12.5** 12.6** 11.4** 9.1**
4.4** 6.7** 8.1** 8.9** 9.3** 10.4 10.3** 11.8** 11.6** 10.5** 8.1**
7.4 10.2 10.5 10.0 9.8 10.2 9.6 9.6 8.6 7.6 6.5
7.1 7.6** 6.5** 6.8** 7.8** 9.2** 9.1* 11.2** 12.2** 11.9** 10.6**
4.6** 7.2** 7.5** 8.7** 9.4 11.4** 9.6 11.7** 11.3** 10.3** 8.2**
7.4 10.4 10.5 9.9 9.8 10.2 9.6 9.6 8.5 7.7 6.5
49.0 8.6 3.3 1.7 37.3
59.6** 9.9** 3.4 1.9* 25.1**
53.9** 10.3** 3.9** 1.9* 29.9**
51.6** 7.9** 3.0* 1.4** 36.1**
40.5** 14.5** 5.2** 3.6** 36.1**
53.9** 10.0** 3.9** 1.9* 30.3**
51.4** 7.9** 2.9** 1.4** 36.4*
69.1 30.9 10.6 20.3
76.8** 23.2** 11.5** 11.8**
76.9** 23.1** 11.2* 11.9**
76.5** 23.5** 10.5 13.0**
78.0** 22.0** 11.3** 10.7**
77.4** 22.6** 11.2** 11.4**
76.6** 23.4** 10.6 12.7**
2.3 97.7
1.7** 98.3**
2.1 97.9
2.0** 98.0**
1.9** 98.1**
2.2 97.8
2.1* 97.9*
72.2 51.3 20.9 4.0 23.7
72.7 49.9** 22.9** 2.7** 24.6**
72.7 50.4* 22.3** 3.1** 24.1
73.3** 50.0** 23.3** 3.3** 23.4
68.6** 44.7** 23.8** 3.5** 27.8**
72.8 49.7** 23.1** 3.3** 23.9
72.9* 49.1** 23.8** 3.8 23.3
7.4 18.0 10.0 27.1 17.5 19.9 0.1
15.6** 17.7 20.3** 15.4** 13.4** 17.4** 0.1
15.1** 17.9 20.0** 15.9** 13.6** 17.4** 0.1
15.1** 18.9** 19.4** 18.0** 12.5** 16.0** 0.1
14.0** 17.4* 20.** 17.3** 11.9** 19.3* 0.1
14.3** 17.1** 20.6** 16.5** 13.5** 17.8** 0.1
14.7** 18.0 20.2** 18.3** 12.4** 16.4** 0.1
Occupation category (employed people)G 17.1** 16.2** 15.2** 24.3** 23.8** 23.9** 58.6** 60.** 61.0**
14.7** 22.6 62.6**
15.5** 23.0 61.4**
14.2** 22.7 60.8**
12.7 22.2 65.1
(continued next page)
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Table 3. (continued ) Estimate
Relationship in householdC Lone person Smoking statusH Never smoked Past smoker Current smoker Average absolute differenceI
ABS (%)
Items asked of all respondents Unweighted Design Final (%) weights (%) weights (%)
Unweighted (%)
Long-form items Design weights (%)
Final weights (%)
8.9
10.3**
12.4**
9.5**
18.0**
11.7**
9.3**
53.7 26.9 19.4
48.9** 31.5** 19.5 2.9
48.0** 30.2** 21.7** 2.5
52.8* 26.5 20.6** 1.5
48.9** 31.5** 19.5 3.2
50.3** 31.7** 18.0** 2.5
53.7 28.6** 17.6** 1.5
The ABS estimates for state, sex and age group were the final estimated residential population as at 30 June 2012 (see http://www.abs.gov.au).59 The ABS figures for marital status, indigenous status and lone households were obtained from the 2011 Census of Population and Housing. The figures relate to individuals aged 16 to 69 years and include people in non-private dwellings (see http://www.abs.gov.au). C These estimates relate to individuals aged at least 15 years. The main English-speaking countries category includes the UK, Ireland, South Africa, Canada, the US and New Zealand.60 D Labour Force Survey estimates for December 2012.61 These estimates relate to individuals aged 15 to 64 years. E These estimates relate to individuals aged 15 to 64 years and exclude people in remote parts of Australia and people in most non-private dwellings (but includes those in boarding schools).62 F Postgraduate degrees include graduate diplomas and graduate certificates. Undergraduate degrees refer to bachelor degrees. A college certificate or diploma refers to advanced diplomas or diplomas. Higher secondary school refers to Years 11 and 12, lower secondary school refers to Year 10. Technical trade certificates refers to Certificates I, II, III or IV. G The ABS estimates come from the Labour Force Survey August 2012.63 ASHR2 uses Australian Standard Classification of Occupations (ASCO) coding64 to match ASHR1, whereas the Labour Force Survey data is coded using the new Australian and New Zealand Standard Classification of Occupations (ANZSCO) system.65 These coding systems are considered sufficiently compatible for valid comparisons of managers and professionals to be made. H ABS estimates for smoking status were obtained from the 2011–12 Australian health survey.66 These estimates relate to individuals aged 15 to 64 years. I Mean of absolute differences between estimates and the ABS benchmarks for the column. A
B
for men and 67.9% for women. Within the mobile phone sample, the participation rate was 66.5%. The overall participation rate was 66.2%. Weighting A two-stage approach was used to weight the data. First, design weights were calculated to adjust for: the probability of each respondent being selected for a landline interview, given the number of landline interviews achieved in relation to the estimated number of residential landlines in Australia as well as the number of landlines and in-scope adults in respondents’ households; the probability of being selected for a mobile phone interview, given the number of mobile phone interviews achieved in relation to the estimated number of mobile phones in Australia; the overlapping chances of selection for persons with both a mobile phone and a landline; and the reduced probability that persons with one partner in the previous year and no homosexual experience would be given the long-form interview. After taking into account the design weights for the study, the sample still demonstrated some deviation from the Australian population in relation to its age–sex distribution and locality. Accordingly, the data were then weighted to match the Australian population on the basis of age, sex, area of residence (i.e. state by Accessibility/Remoteness Index of Australia (ARIA) category of urban, regional or remote47) and telephone ownership (i.e. mobile telephone only vs other), using population benchmarks provided by the Australian Bureau of Statistics (Table 3). This resulted in a weighted sample of 20 094 people (10 056 men and 10 038 women).
For questions asked of all respondents, final weights were constrained to be between 0.2 and 5, with a mean of 1. For questions asked only in long-form interviews, no constraints were used and the final weights ranged from 0.15 to 28.4, with a mean of 2.34. All analyses use these final weights, using the survey estimation commands in Stata Version 11.2.48 The design effects were 1.366 for men and 1.343 for women, giving effective sample sizes of 7294 men and 7542 women, and a total of 14 836. As can be seen, after adjusting for location, age and sex, the sample was consistent with the 2011 Census with regard to these variables. The sample appears to slightly overrepresent married people, although it is possible that this reflects respondents describing themselves as married while actually living in what is legally a de facto relationship. Given that the interviews were only conducted in English, it is not surprising that overseas-born people from nonEnglish-speaking countries are under-represented. Australia has no single large language group whose members have a high proportion of non-English speakers (like Spanish speakers in the USA), and it would have been prohibitively expensive to translate and program foreign-language interviews and to train interviewers for other languages. People who were in part-time employment were somewhat over-represented and people in full-time employment were somewhat under-represented, presumably because the latter were busy and harder to reach. Those in managerial occupations were over-represented and those with lower levels of education and smokers were under-represented. Given the correlation between these three variables, this seems likely to represent a single form of bias.
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Table 4. Sociodemographic profile of the sample: weighted frequencies (and column percentages) Data show the number of individuals in each group, with percentages in parentheses
Age (years) 16–19 20–29 30–39 40–49 50–59 60–69 Language spoken at home English Other Missing Education Less than secondary Secondary Post-secondary Don’t know/Can’t remember Refused Region Major city Regional Remote Don’t knowB RefusedB MissingB Household income $28 000 $28 001–$52 000 $52 001–$83 000 $83 001–$125 000 > $125 000 Refused Missing Occupation Blue collar White collar Manager/professional Never worked Refused
Men (n = 10 056)
Women (n = 10 038)
778 2060 1899 1917 1852 1551
713 2105 2072 2056 1806 1286
(7.7) (20.5) (18.9) (19.1) (18.4) (15.4)
(7.1) (21.0) (20.6) (20.5) (18.0) (12.8)
TotalA (n = 20 094) 1491 4165 3971 3973 3658 2836
(7.4) (20.7) (19.8) (19.8) (18.2) (14.1)
9217 (91.7) 838 (8.3) 2 (0.0)
9353 (93.2) 685 (6.8) 0
18 570 (92.4) 1523 (7.6) 2 (0.0)
1513 3688 4845 4 7
(15.0) (36.7) (48.2) (0.0) (0.1)
1702 2437 5891 2 6
(17.0) (24.3) (58.7) (0.0) (0.1)
3215 6125 10 736 6 13
(16.0) (30.5) (53.4) (0.0) (0.1)
6837 2775 245 66 37 96
(68.0) (27.6) (2.4) (0.7) (0.4) (1.0)
6904 2780 202 39 42 71
(68.8) (27.7) (2.0) (0.4) (0.4) (0.7)
13 741 5554 447 106 78 167
(68.4) (27.6) (2.2) (0.5) (0.4) (0.8)
1274 1356 1973 2014 2768 671 2
(12.7) (13.5) (19.6) (20.0) (27.5) (6.7) (0.0)
1593 (15.9) 1523 (15.2) 1948 (19.4) 1949 (19.4) 2124 (21.2) 901 (9.0) 0
2866 2879 3921 3963 4892 1572 2
(14.3) (14.3) (19.5) (19.7) (24.3) (7.8) (0.0)
3533 2316 3992 153 62
(35.1) (23.0) (39.7) (1.5) (0.6)
1111 5016 3683 161 67
4644 7332 7675 314 130
(23.1) (36.5) (38.2) (1.6) (0.6)
(11.1) (50.0) (36.7) (1.6) (0.7)
A
Frequency totals may differ by one due to rounding. Postcode or location data missing for allocation to ARIA region.
B
Table 4 presents the main sociodemographic factors used as correlates of sexual behaviours in many of the accompanying papers, allowing readers to see what proportion of the sample belonged to each group. Respondent embarrassment and honesty As shown in Table 5, 90% of the respondents were either ‘not at all’ embarrassed by the questionnaire or ‘slightly’ embarrassed (Box 1). Furthermore, 89% of respondents reported having been ‘entirely honest’ in their responses to questions, with another 10% being honest at least 90% of the time (Table 6; Box 1). c2 tests were used to check for significant correlates of embarrassment and honesty shown in Tables 5 and 6. Women (12.6%) were more likely to report more than slight embarrassment than men (7.2%; P < 0.001). Higher levels of
embarrassment were reported by people who were: younger (P < 0.001), did not speak English at home (P < 0.001), had completed post-secondary education (P < 0.001), lived in major cities or remote areas (P < 0.001), had low incomes (P < 0.001), or had white-collar or managerial occupations (P < 0.001). The likelihood of being less than 90% honest in responding to the survey was significantly greater among men who did not speak English at home (P = 0.006) or had very low incomes (P < 0.001). The likelihood of being less than 90% honest in responding to the survey was significantly greater among women who did not speak English at home (P < 0.001) or lived in major cities (P = 0.02). Presentation of statistics Most percentages are given in the papers in this issue without standard errors or 95% confidence intervals. This decision was
Design and methods of ASHR2
Table 5.
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Sociodemographic correlates of the degree of embarrassment reported in completing the interview
Correlate
Degree of embarrassment Quite, very or extremely embarrassing (%)
Overall Age (years) 16–19 20–29 30–39 40–49 50–59 60–69 Language spoken at home English Other Education Less than secondary Secondary Post-secondary Region of residence Major city Regional Remote Household income group $28 000 $28 001–$52 000 $52 001–$83 000 $83 001–$125 000 > $125 000 Occupational category Blue collar White collar Manager/professional
Men (n = 10 043) Slightly embarrassing (%)
Not at all embarrassing (%)
Quite, very or extremely embarassing (%)
Women (n = 10 025) Slightly embarrassing (%)
Not at all embarrassing (%)
7.2
27.9
64.9
12.6
34.9
52.4
9.1 9.1 7.7 7.0 5.5 5.2
33.3 30.2 28.7 28.9 26.8 21.1
57.6 60.7 63.6 64.1 67.6 73.7
13.1 15.6 14.7 12.5 10.4 7.8
35.4 38.8 37.8 36.8 32.6 24.1
51.6 45.7 47.5 50.7 57.1 68.2
6.3 16.7
28.1 25.6
65.6 57.7
11.8 24.5
35.1 32.2
53.1 43.3
5.9 6.9 7.7
24.9 24.5 31.4
69.2 68.5 60.9
9.8 11.7 13.8
30.1 35.5 36.1
60.2 52.8 50.1
7.7 5.4 8.4
29.1 25.1 24.8
63.1 69.5 66.8
13.4 10.5 11.3
35.7 32.9 37.1
50.9 56.7 51.6
9.2 6.9 6.7 6.1 6.1
25.4 25.6 27.3 29.5 28.4
65.4 67.5 66.0 64.3 65.5
14.0 10.1 12.4 10.8 12.6
31.0 32.0 35.5 39.2 36.3
55.0 57.9 52.1 50.0 51.1
6.2 7.9 7.4
23.8 29.6 29.7
70.0 62.5 62.9
10.7 12.6 12.9
30.4 35.5 35.7
58.9 51.9 51.4
Box 1.
Ascertainment of embarrassment and honesty
That’s the end of the study questions, but I’d also like to ask some quick questions about the questionnaire. How embarrassing did you find the questionnaire? *
Extremely embarrassing
*
Very embarrassing
*
Quite embarrassing
*
Slightly embarrassing
*
Not at all embarrassing
In percentage terms, how honest were you in your answers to the questionnaire?
made to maximise both readability and brevity and is consistent with the style of reporting of studies of similar scope and intent.1,3,49 Figure 1 displays approximate standard errors for observed percentages in subsamples of different sizes, both for questions asked of all participants and for those in the long-form survey
only (marked L). As can be seen, when the entire sample is employed for questions asked of everyone, the standard error remains below 0.5 percentage points. Thus, using a normal approximation, the 95% confidence interval for any estimate involving the entire sample will be less than 1 percentage points. Similarly, when approximately half the sample is used, or
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Table 6. Sociodemographic correlates of the degree of honesty reported in relation to answers given during the interview Correlate
Overall Age (years) 16–19 20–29 30–39 40–49 50–59 60–69 Language spoken at home English Other Education Less than secondary Secondary Post-secondary Region of residence Major city Regional Remote Household income group $28 000 $28 001–$52 000 $52 001–$83 000 $83 001–$125 000 > $125 000 Occupational category Blue collar White collar Manager/professional
