Women & Health, 55:58–76, 2015 Copyright © Taylor & Francis Group, LLC ISSN: 0363-0242 print/1541-0331 online DOI: 10.1080/03630242.2014.972017
Reliability and Validity of the Menopausal Symptom Scale MYUNG SOOK CHOI, PhD, RN Department of Nursing, Seoil University, Seoul, Korea
HYUNJEONG SHIN, PhD, RN College of Nursing, Korea University, Seoul, Korea
Menopausal symptom experiences differ by racial/ethnic group. Thus, health care professionals who use instruments to measure menopausal symptoms need to be aware of cultural sensitivities. The purpose of this study was to examine the psychometric properties of the Menopausal Symptom Scale among Korean women. Data from 229 Korean women between the ages of 40 and 65 years, selected by convenience sampling, were collected during 2010–2011. Psychometric properties were evaluated through content validity and item analysis, construct validity, discriminant validity, criterion-related validity, floor/ceiling effects, and internal consistency reliability. Exploratory and confirmatory factor analyses revealed four factors explaining 65% of variance in the items. Discriminant validity and the criterion-related validity were supported. No significant floor/ceiling effects were found. Cronbach’s alpha values ranged from 0.90 to 0.95. The Menopausal Symptom Scale developed for Korean menopausal women appeared to be a valid and reliable instrument. It appeared that it measured psychological symptoms more comprehensively and in a culturally-specific or ethnic-specific manner in menopausal women of Asian or traditional cultures. It will be necessary to broaden the scale of research to other ethnic groups and countries to verify the psychometric properties specific to the ethnic group or country.
Received August 13, 2013; revised March 6, 2014; accepted March 13, 2014. Address correspondence to Hyunjeong Shin, PhD, RN, College of Nursing, Korea University, 145 Anam-ro, Sungbuk-gu, Seoul 136-705, Korea. E-mail: [email protected]
58
Reliability of Validity of Menopausal Symptom Scale
KEYWORDS symptoms
59
instruments, menopause, reliability and validity,
INTRODUCTION Menopausal symptoms have comprised an important area of concern in menopause research (Berg, Larson, and Pasvogel 2008). The whole process of transition from premenopause to postmenopause may take more than 10 years (Alder 2002). Many women experience several physical and psychological symptoms, such as hot flushes, night sweats, vaginal dryness, sleep disturbance, increased depressive symptoms, and difficulty concentrating during and after these years (Freedman 2002; Kravitz et al. 2008; Mishra and Kuh 2010). In many women, these symptoms may be severe enough to affect their quality of life and lead to seeking health care and treatment (Williams et al. 2007). Menopausal symptom experiences differ by racial/ethnic group, and to some extent, may be culturally constructed (Fu, Anderson, and Courtney 2003; Gold et al. 2006; Im 2007; Travers et al. 2005). Western cultures tend to value youth and beauty, which may medicalize the menopausal transition, and have considered menopausal hormone therapy as a main method for relieving physical and psychological symptoms during the menopausal transition (Defey et al. 1996). Even though Western women tend to see menopause as a normal/neutral phase of their life cycle, in a recent study they mentioned a higher number of negative consequences (e.g., concerns about weight gain, disease appearance or aggravation, and aging) than positive consequences (e.g., cessation of menses) (Pimenta et al. 2011). Traditional Asians consider menopause as being both natural and miserable with an achievement of “wise woman status” and a loss of womanhood, which is represented by fertility, and tend to complain less of menopausal symptoms (Hall et al. 2007; Lim and Mackey, 2012). Nonetheless, the Western cultural concept has been a basis for health care for menopausal women (Fu, Anderson, and Courtney 2003). Health-care professionals who use instruments to measure menopausal symptoms need to pay attention to cultural sensitivities, because social norms, beliefs, and moral values of a culture can affect the reliability and validity of the instrument (Lee, Im, and Chee 2010; Waltz, Strickland, and Lenz 2005). Studies have used several scales to measure menopausal symptoms (Freeman et al. 2003; Greene 1998; Im 2006; Schneider et al. 2000). Most of them are very short, consisting of 10–21 physical and psychological items (Berg, Larson, and Pasvogel 2008; Freeman et al. 2003; Schneider et al. 2000), while one scale has more than 70 items measuring physical, psychological, and psychosomatic symptoms (Im 2006). Most scales were developed for European or American Caucasian women. Thus, these scales have limitations
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M. S. Choi and H. Shin
when used in other ethnic groups (Gharaibeh, Al-Obeisat, and Hattab 2010). A previous study, which used one of the existing scales among Australian and Taiwanese women, reported a low reliability coefficient in the sample of Taiwanese women (Cronbach’s alpha = 0.63) while reporting adequate reliability among Australian women (Cronbach’s alpha = 0.85) (Fu, Anderson, and Courtney 2003). Another study, which compared psychometric properties of a scale in multiethnic groups, also reported that it may work better for Caucasians compared with Asian or Hispanic women (Lee, Im, and Chee 2010). Gharaibeh, Al-Obeisat, and Hattab (2010) recommended developing instruments to measure menopausal symptoms that are sensitive to the woman’s local cultures. The Menopausal Symptom Scale (MSS) was initially developed for Korean women to measure menopausal symptoms during their menopausal transition (Choi 2002). Initially, it included 81 items based on evidence from relevant research, interviews with menopausal women, reference to experts and author opinions, and existing scales. Following the pilot work of 69 Korean menopausal women (40–65 years old), 37 of 81 items were removed, leaving 44 items (Choi 2002). The original version of the MSS with 44 items consists of 4 dimensions: 7 items on vasomotor symptoms, 5 items on urogenital symptoms, 11 items on physical symptoms, and 21 items on psychological symptoms. In the initial study of 35 postmenopausal women, Cronbach’s alpha coefficient was 0.92. MSS items use a 6-point Likert-type response to identify symptoms during the menopausal transition, ranging from 0 (not at all) to 5 (extremely). Examples of items included “I sweat severely at night” and “I feel down or depressed more often than before.” Higher scores indicate more severe symptom experiences. Despite the fact that the MSS shows good reliability, no other studies have assessed its psychometric properties. Classification of the items into four dimensions was based on previous literature and the author’s knowledge; thus, they need to be confirmed through the factor analytic approach. Also, instrument reliability needs to be assessed with a larger sample consisting of women in a variety of menopausal stages. Thus, the purpose of the present study was to evaluate the psychometric properties of the MSS in Korean women experiencing the menopausal transition. We selected measurement properties for the evaluation of the scale based on Terwee et al.’s (2007) study. They suggested eight measurement properties for the evaluation of health status questionnaires: content validity, internal consistency, criterion validity, construct validity, reproducibility, responsiveness, floor and ceiling effects, and interpretability. Among them, we tested the following six properties: (1) content validity and item analysis, (2) construct validity, (3) discriminant validity, (4) criterion-related validity, (5) floor/ceiling effects, and (6) internal consistency. We evaluated discriminant validity instead of
Reliability of Validity of Menopausal Symptom Scale
61
“responsiveness,” which is one of the eight measurement properties, because the latter was not testable due to the cross-sectional nature of this study.
METHODS Study Design and Participants This study was a secondary analysis of data from a larger study of influencing factors for menopausal quality of life with a sample of Korean women (Shin and Park in prep). The larger study was designed to test a hypothetical model of health-related quality of life in women during menopausal transition. We recruited the participants from community settings (i.e., beauty shop, department store) using a convenience sampling method from September 2010 to January 2011. Eligibility criteria included: (1) 40–65 years of age, (2) not being pregnant or breastfeeding, and (3) Korean women who can read and understand Korean. Of the 304 women who were invited to participate in the study, none were pregnant or breastfeeding. All of them could read and understand Korean. No one refused to participate. Thus, the eligibility rate and the participation rate were each 100%. Among the 304 women enrolled in the study, 229 women (75.3%) completed all of the following questionnaires and were included in the analyses for the present study: the MSS, Center for Epidemiological Studies Depression (CES-D), and Attitude Toward Menopause Scale (ATMS). A trained research assistant collected the data. The required sample size for correlation methods (two-tailed) was approximately 157 to detect a medium correlation size (r = 0.30) with an alpha of 0.01, and power of 0.90 and was 96 for ANCOVA (for known-group validity test) with an alpha of 0.01 (u = 2) to detect a medium effect size (f = 0.25) with a power of 0.90 (Cohen et al. 2003).
Ethical Considerations We obtained approval for the study protocol from the University Institutional Review Board. All participants were given information about the right to withdraw from the study without any disadvantages. All participants signed the informed consent form, which guaranteed anonymity and confidentiality.
Relevant Measures MENOPAUSAL STATUS Menopausal status was categorized as: (1) premenopausal, menstruations in the previous 3 months with no increase in irregularity; (2) perimenopausal, menstrual bleeding in the previous 3 months with increasing irregularity
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M. S. Choi and H. Shin
or menstrual bleeding in the previous 12 months, but not in the previous 3 months; or (3) postmenopausal, no menstrual bleeding in the previous 12 months (Freeman et al. 2003). Women who had a hysterectomy and/or a bilateral oophorectomy were separately categorized as surgically postmenopausal. CENTER
FOR
EPIDEMIOLOGICAL STUDIES DEPRESSION SCALE (CES-D)
The CES-D was originally developed by Radloff (1977) to measure depressive symptoms. In the present study, we used the Korean version of the CES-D (Chon and Rhee 1992). It is composed of 20 items assessing how often the individual has had depressive symptoms in the past week. It is a 4point Likert scale with higher scores indicating higher levels of depressive symptoms. Cronbach’s alpha coefficient was greater than 0.84 when it was developed (Radloff 1977) and was 0.88 in the present study. ATTITUDE TOWARD MENOPAUSE SCALE (ATMS) The ATMS was originally developed by Neugarten et al. (1963). In the current study, a 27-item instrument translated into Korean (Choi 2002) was used. It is a 4-point Likert scale from 1 to 4. Higher scores indicate more positive attitudes. Cronbach’s alpha coefficient was 0.94 when it was translated and revised (Choi 2002), and was 0.73 in the current study.
Data Analysis For statistical analysis we used SPSS version 21.0 for Windows and AMOS version 21.0. First, content validity was examined and item analysis was conducted. To assess content validity, five nursing faculty members and a physician of gynecology rated each of the items for relevance to the symptoms the woman might have experienced during the menopausal transition. A 4-point rating scale was used, ranging from 1 (not relevant) to 4 (very relevant). A Content Validity Index (CVI) was calculated to quantify the extent of agreement among the experts. To confirm item homogeneity of the MSS, an inter-item correlation analysis was conducted. Second, we evaluated construct validity through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). For factor analysis, we divided participants into two sub-samples using the random sample cases function in SPSS. EFA was applied in one sample (n = 115) and CFA was performed on the second half of the samples (n = 114). EFA was conducted using principal component analyses with varimax rotations. For CFA, unweighted least square (ULS) estimation was used to confirm the structure of the MSS because it is more stable than weighted least squares in small
Reliability of Validity of Menopausal Symptom Scale
63
samples and gives more reliable parameter estimates (Flora and Curran 2004; Forero, Maydeu-Olivares, and Gallardo-Pujol 2009). The model-data fit was evaluated by goodness-of-fit indices. The measures of fit criterion for an acceptable model included the chi square/degree of freedom ratio (CMIN/DF < 3), goodness-of-fit index (GFI > 0.90), Normed Fit Index (NFI > 0.90), and Root Mean Square Residual (RMR < 0.05) (Hu and Bentler 1999; Kaariainen et al. 2011). Third, discriminant validity was tested using known-group validation, which involves demonstrating the fact that the MSS can differentiate members of each menopausal status on the basis of their scale scores using ANCOVA. To obtain the purer effect of group differences on the MSS, age was controlled. In this study, we hypothesized that we would observe significant differences in MSS scores among the three menopausal stage categories. Previous studies also performed a similar approach (Lee, Im, and Chee 2010; Travers et al. 2005) using a scale for menopausal symptoms to distinguish three or four menopausal status categories. Fourth, criterion-related validity was evaluated through examination of correlations between the MSS and measures of theoretically related constructs. Criterion-related validity shows the extent of the relationship between an instrument and factors that are theoretically expected to be associated with it (DeVon et al. 2007; Roberts, Dolansky, and Weber 2010). Based on the literature, depressive symptoms and attitude toward menopause were expected to be related to menopausal symptoms (Ayers, Forshaw, and Hunter 2010; Chedraui et al. 2009; Hall et al. 2007; Lee and Kim 2008; Nosek et al. 2010; Shea 2006; Strauss 2011; Yen et al. 2009). Fifth, descriptive statistics were calculated to identify floor/ceiling effects, which may be present when more than 15% of the sample have the lowest or highest possible scores (Monticone et al. 2013). If foor or ceiling effects are present, it may indicate limited content validity and reliability. Also, responsiveness would be limited because changes cannot be measured enough (Terwee et al. 2007). Finally, we evaluated internal consistency reliability using Cronbach’s alpha coefficients.
RESULTS Sample Characteristics The mean age of the participants was 50.50 years (SD = 5.05) (Table 1). Most participants were married or partnered (84.3%), had completed high school or less (77.3%), and perceived their economic level as middle or low class (90.4%). About two-thirds of the participants (65.9%) were unemployed. About half of the participants (51.5%) had normal (18.5 ≤ body mass index 0.80, indicating redundancy of these items (Ferketich 1991): I am easily upset and irritated
Reliability of Validity of Menopausal Symptom Scale
65
and I often get angry over minor issues; I feel tense and I get impatient; and I sweat severely at night and I have cold sweats during the day. The coefficients between I have more facial hair on my face than before and most other items were
Reliability and Validity of the Menopausal Symptom Scale MYUNG SOOK CHOI, PhD, RN Department of Nursing, Seoil University, Seoul, Korea
HYUNJEONG SHIN, PhD, RN College of Nursing, Korea University, Seoul, Korea
Menopausal symptom experiences differ by racial/ethnic group. Thus, health care professionals who use instruments to measure menopausal symptoms need to be aware of cultural sensitivities. The purpose of this study was to examine the psychometric properties of the Menopausal Symptom Scale among Korean women. Data from 229 Korean women between the ages of 40 and 65 years, selected by convenience sampling, were collected during 2010–2011. Psychometric properties were evaluated through content validity and item analysis, construct validity, discriminant validity, criterion-related validity, floor/ceiling effects, and internal consistency reliability. Exploratory and confirmatory factor analyses revealed four factors explaining 65% of variance in the items. Discriminant validity and the criterion-related validity were supported. No significant floor/ceiling effects were found. Cronbach’s alpha values ranged from 0.90 to 0.95. The Menopausal Symptom Scale developed for Korean menopausal women appeared to be a valid and reliable instrument. It appeared that it measured psychological symptoms more comprehensively and in a culturally-specific or ethnic-specific manner in menopausal women of Asian or traditional cultures. It will be necessary to broaden the scale of research to other ethnic groups and countries to verify the psychometric properties specific to the ethnic group or country.
Received August 13, 2013; revised March 6, 2014; accepted March 13, 2014. Address correspondence to Hyunjeong Shin, PhD, RN, College of Nursing, Korea University, 145 Anam-ro, Sungbuk-gu, Seoul 136-705, Korea. E-mail: [email protected]
58
Reliability of Validity of Menopausal Symptom Scale
KEYWORDS symptoms
59
instruments, menopause, reliability and validity,
INTRODUCTION Menopausal symptoms have comprised an important area of concern in menopause research (Berg, Larson, and Pasvogel 2008). The whole process of transition from premenopause to postmenopause may take more than 10 years (Alder 2002). Many women experience several physical and psychological symptoms, such as hot flushes, night sweats, vaginal dryness, sleep disturbance, increased depressive symptoms, and difficulty concentrating during and after these years (Freedman 2002; Kravitz et al. 2008; Mishra and Kuh 2010). In many women, these symptoms may be severe enough to affect their quality of life and lead to seeking health care and treatment (Williams et al. 2007). Menopausal symptom experiences differ by racial/ethnic group, and to some extent, may be culturally constructed (Fu, Anderson, and Courtney 2003; Gold et al. 2006; Im 2007; Travers et al. 2005). Western cultures tend to value youth and beauty, which may medicalize the menopausal transition, and have considered menopausal hormone therapy as a main method for relieving physical and psychological symptoms during the menopausal transition (Defey et al. 1996). Even though Western women tend to see menopause as a normal/neutral phase of their life cycle, in a recent study they mentioned a higher number of negative consequences (e.g., concerns about weight gain, disease appearance or aggravation, and aging) than positive consequences (e.g., cessation of menses) (Pimenta et al. 2011). Traditional Asians consider menopause as being both natural and miserable with an achievement of “wise woman status” and a loss of womanhood, which is represented by fertility, and tend to complain less of menopausal symptoms (Hall et al. 2007; Lim and Mackey, 2012). Nonetheless, the Western cultural concept has been a basis for health care for menopausal women (Fu, Anderson, and Courtney 2003). Health-care professionals who use instruments to measure menopausal symptoms need to pay attention to cultural sensitivities, because social norms, beliefs, and moral values of a culture can affect the reliability and validity of the instrument (Lee, Im, and Chee 2010; Waltz, Strickland, and Lenz 2005). Studies have used several scales to measure menopausal symptoms (Freeman et al. 2003; Greene 1998; Im 2006; Schneider et al. 2000). Most of them are very short, consisting of 10–21 physical and psychological items (Berg, Larson, and Pasvogel 2008; Freeman et al. 2003; Schneider et al. 2000), while one scale has more than 70 items measuring physical, psychological, and psychosomatic symptoms (Im 2006). Most scales were developed for European or American Caucasian women. Thus, these scales have limitations
60
M. S. Choi and H. Shin
when used in other ethnic groups (Gharaibeh, Al-Obeisat, and Hattab 2010). A previous study, which used one of the existing scales among Australian and Taiwanese women, reported a low reliability coefficient in the sample of Taiwanese women (Cronbach’s alpha = 0.63) while reporting adequate reliability among Australian women (Cronbach’s alpha = 0.85) (Fu, Anderson, and Courtney 2003). Another study, which compared psychometric properties of a scale in multiethnic groups, also reported that it may work better for Caucasians compared with Asian or Hispanic women (Lee, Im, and Chee 2010). Gharaibeh, Al-Obeisat, and Hattab (2010) recommended developing instruments to measure menopausal symptoms that are sensitive to the woman’s local cultures. The Menopausal Symptom Scale (MSS) was initially developed for Korean women to measure menopausal symptoms during their menopausal transition (Choi 2002). Initially, it included 81 items based on evidence from relevant research, interviews with menopausal women, reference to experts and author opinions, and existing scales. Following the pilot work of 69 Korean menopausal women (40–65 years old), 37 of 81 items were removed, leaving 44 items (Choi 2002). The original version of the MSS with 44 items consists of 4 dimensions: 7 items on vasomotor symptoms, 5 items on urogenital symptoms, 11 items on physical symptoms, and 21 items on psychological symptoms. In the initial study of 35 postmenopausal women, Cronbach’s alpha coefficient was 0.92. MSS items use a 6-point Likert-type response to identify symptoms during the menopausal transition, ranging from 0 (not at all) to 5 (extremely). Examples of items included “I sweat severely at night” and “I feel down or depressed more often than before.” Higher scores indicate more severe symptom experiences. Despite the fact that the MSS shows good reliability, no other studies have assessed its psychometric properties. Classification of the items into four dimensions was based on previous literature and the author’s knowledge; thus, they need to be confirmed through the factor analytic approach. Also, instrument reliability needs to be assessed with a larger sample consisting of women in a variety of menopausal stages. Thus, the purpose of the present study was to evaluate the psychometric properties of the MSS in Korean women experiencing the menopausal transition. We selected measurement properties for the evaluation of the scale based on Terwee et al.’s (2007) study. They suggested eight measurement properties for the evaluation of health status questionnaires: content validity, internal consistency, criterion validity, construct validity, reproducibility, responsiveness, floor and ceiling effects, and interpretability. Among them, we tested the following six properties: (1) content validity and item analysis, (2) construct validity, (3) discriminant validity, (4) criterion-related validity, (5) floor/ceiling effects, and (6) internal consistency. We evaluated discriminant validity instead of
Reliability of Validity of Menopausal Symptom Scale
61
“responsiveness,” which is one of the eight measurement properties, because the latter was not testable due to the cross-sectional nature of this study.
METHODS Study Design and Participants This study was a secondary analysis of data from a larger study of influencing factors for menopausal quality of life with a sample of Korean women (Shin and Park in prep). The larger study was designed to test a hypothetical model of health-related quality of life in women during menopausal transition. We recruited the participants from community settings (i.e., beauty shop, department store) using a convenience sampling method from September 2010 to January 2011. Eligibility criteria included: (1) 40–65 years of age, (2) not being pregnant or breastfeeding, and (3) Korean women who can read and understand Korean. Of the 304 women who were invited to participate in the study, none were pregnant or breastfeeding. All of them could read and understand Korean. No one refused to participate. Thus, the eligibility rate and the participation rate were each 100%. Among the 304 women enrolled in the study, 229 women (75.3%) completed all of the following questionnaires and were included in the analyses for the present study: the MSS, Center for Epidemiological Studies Depression (CES-D), and Attitude Toward Menopause Scale (ATMS). A trained research assistant collected the data. The required sample size for correlation methods (two-tailed) was approximately 157 to detect a medium correlation size (r = 0.30) with an alpha of 0.01, and power of 0.90 and was 96 for ANCOVA (for known-group validity test) with an alpha of 0.01 (u = 2) to detect a medium effect size (f = 0.25) with a power of 0.90 (Cohen et al. 2003).
Ethical Considerations We obtained approval for the study protocol from the University Institutional Review Board. All participants were given information about the right to withdraw from the study without any disadvantages. All participants signed the informed consent form, which guaranteed anonymity and confidentiality.
Relevant Measures MENOPAUSAL STATUS Menopausal status was categorized as: (1) premenopausal, menstruations in the previous 3 months with no increase in irregularity; (2) perimenopausal, menstrual bleeding in the previous 3 months with increasing irregularity
62
M. S. Choi and H. Shin
or menstrual bleeding in the previous 12 months, but not in the previous 3 months; or (3) postmenopausal, no menstrual bleeding in the previous 12 months (Freeman et al. 2003). Women who had a hysterectomy and/or a bilateral oophorectomy were separately categorized as surgically postmenopausal. CENTER
FOR
EPIDEMIOLOGICAL STUDIES DEPRESSION SCALE (CES-D)
The CES-D was originally developed by Radloff (1977) to measure depressive symptoms. In the present study, we used the Korean version of the CES-D (Chon and Rhee 1992). It is composed of 20 items assessing how often the individual has had depressive symptoms in the past week. It is a 4point Likert scale with higher scores indicating higher levels of depressive symptoms. Cronbach’s alpha coefficient was greater than 0.84 when it was developed (Radloff 1977) and was 0.88 in the present study. ATTITUDE TOWARD MENOPAUSE SCALE (ATMS) The ATMS was originally developed by Neugarten et al. (1963). In the current study, a 27-item instrument translated into Korean (Choi 2002) was used. It is a 4-point Likert scale from 1 to 4. Higher scores indicate more positive attitudes. Cronbach’s alpha coefficient was 0.94 when it was translated and revised (Choi 2002), and was 0.73 in the current study.
Data Analysis For statistical analysis we used SPSS version 21.0 for Windows and AMOS version 21.0. First, content validity was examined and item analysis was conducted. To assess content validity, five nursing faculty members and a physician of gynecology rated each of the items for relevance to the symptoms the woman might have experienced during the menopausal transition. A 4-point rating scale was used, ranging from 1 (not relevant) to 4 (very relevant). A Content Validity Index (CVI) was calculated to quantify the extent of agreement among the experts. To confirm item homogeneity of the MSS, an inter-item correlation analysis was conducted. Second, we evaluated construct validity through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). For factor analysis, we divided participants into two sub-samples using the random sample cases function in SPSS. EFA was applied in one sample (n = 115) and CFA was performed on the second half of the samples (n = 114). EFA was conducted using principal component analyses with varimax rotations. For CFA, unweighted least square (ULS) estimation was used to confirm the structure of the MSS because it is more stable than weighted least squares in small
Reliability of Validity of Menopausal Symptom Scale
63
samples and gives more reliable parameter estimates (Flora and Curran 2004; Forero, Maydeu-Olivares, and Gallardo-Pujol 2009). The model-data fit was evaluated by goodness-of-fit indices. The measures of fit criterion for an acceptable model included the chi square/degree of freedom ratio (CMIN/DF < 3), goodness-of-fit index (GFI > 0.90), Normed Fit Index (NFI > 0.90), and Root Mean Square Residual (RMR < 0.05) (Hu and Bentler 1999; Kaariainen et al. 2011). Third, discriminant validity was tested using known-group validation, which involves demonstrating the fact that the MSS can differentiate members of each menopausal status on the basis of their scale scores using ANCOVA. To obtain the purer effect of group differences on the MSS, age was controlled. In this study, we hypothesized that we would observe significant differences in MSS scores among the three menopausal stage categories. Previous studies also performed a similar approach (Lee, Im, and Chee 2010; Travers et al. 2005) using a scale for menopausal symptoms to distinguish three or four menopausal status categories. Fourth, criterion-related validity was evaluated through examination of correlations between the MSS and measures of theoretically related constructs. Criterion-related validity shows the extent of the relationship between an instrument and factors that are theoretically expected to be associated with it (DeVon et al. 2007; Roberts, Dolansky, and Weber 2010). Based on the literature, depressive symptoms and attitude toward menopause were expected to be related to menopausal symptoms (Ayers, Forshaw, and Hunter 2010; Chedraui et al. 2009; Hall et al. 2007; Lee and Kim 2008; Nosek et al. 2010; Shea 2006; Strauss 2011; Yen et al. 2009). Fifth, descriptive statistics were calculated to identify floor/ceiling effects, which may be present when more than 15% of the sample have the lowest or highest possible scores (Monticone et al. 2013). If foor or ceiling effects are present, it may indicate limited content validity and reliability. Also, responsiveness would be limited because changes cannot be measured enough (Terwee et al. 2007). Finally, we evaluated internal consistency reliability using Cronbach’s alpha coefficients.
RESULTS Sample Characteristics The mean age of the participants was 50.50 years (SD = 5.05) (Table 1). Most participants were married or partnered (84.3%), had completed high school or less (77.3%), and perceived their economic level as middle or low class (90.4%). About two-thirds of the participants (65.9%) were unemployed. About half of the participants (51.5%) had normal (18.5 ≤ body mass index 0.80, indicating redundancy of these items (Ferketich 1991): I am easily upset and irritated
Reliability of Validity of Menopausal Symptom Scale
65
and I often get angry over minor issues; I feel tense and I get impatient; and I sweat severely at night and I have cold sweats during the day. The coefficients between I have more facial hair on my face than before and most other items were
