551287
research-article2014
VAWXXX10.1177/1077801214551287Clear et al.Violence Against Women
Article
Sexual Harassment Victimization and Perpetration Among High School Students
Violence Against Women 2014, Vol. 20(10) 1203–1219 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1077801214551287 vaw.sagepub.com
Emily R. Clear1, Ann L. Coker1, Patricia G. Cook-Craig1, Heather M. Bush1, Lisandra S. Garcia1, Corrine M. Williams1, Alysha M. Lewis1, and Bonnie S. Fisher2
Abstract This large, population-based study is one of the few to examine prevalence rates of sexual harassment occurring during the past 12 months by victimization and perpetration among adolescents. In this large, cross-sectional survey of students attending 26 high schools, sexual harassment was defined using three questions from the Sexual Experiences Questionnaire. Among 18,090 students completing the survey, 30% disclosed sexual harassment victimization (37% of females, 21% of males) and 8.5% reported perpetration (5% of females, 12% of males). Sexual harassment perpetration was highly correlated with male sex, minority race/ethnicity, same-sex attraction, bullying, alcohol binge drinking, and intraparental partner violence. Keywords adolescents, high school, perpetration, sexual harassment, victimization Although sexual harassment has often been associated with the adult workplace environment, a shift toward exploring rates in high school-aged adolescents has emerged (Fineran & Bennett, 1999; Fineran & Bolen, 2006; Hill, Kearl, & American Association
1University 2University
of Kentucky, Lexington, KY, USA of Cincinnati, OH, USA
Corresponding Author: Emily R. Clear, Department of Obstetrics and Gynecology, A. B. Chandler Medical Center, University of Kentucky, 800 Rose Street, C347, Lexington, KY 40536-0293, USA. Email: [email protected]
1204
Violence Against Women 20(10)
of University Women, 2011). Sexual harassment as it relates to the school environment is defined as conduct that is sexual in nature, unwelcome, denies or limits a student’s ability to participate in or benefit from a school’s education program, and interferes with a student’s right to a supportive, respectful, and safe learning environment (U.S. Department of Education, Office for Civil Rights, 2008; Witkowska & Kjellberg, 2005). School-based definitions also address unwanted sexual behavior that interferes with a student’s educational opportunities, which may not be face-to-face, including cyberbullying through text messages and other social media (Hill et al., 2011). It is worth noting the difference between bullying and sexual harassment. Unlike bullying behaviors, sexual harassment incorporates a strong sexual component with little to no physical contact. Sexual harassment is an illegal form of sex discrimination that violates Title VII of the Civil Rights Act of 1964 (U.S. Equal Employment Opportunity Commission, 2009) and Title IX of the Education Amendments of 1972 (U.S. Department of Education, Office for Civil Rights, 1997). When bullying is used to describe sexual harassment, it takes away the role of gender and sex, which are key parts of the definition (Stein & Mennemeier, 2011). Nansel and colleagues used a definition that addressed the three components used in bullying definitions among researchers: Bullying is a specific type of aggression in which (1) the behavior is intended to harm or disturb, (2) the behavior occurs repeatedly over time, (3) there is an imbalance of power (physical or psychological), with a more powerful person or group attacking a less powerful one. (Nansel et al., 2001, p. 2094; Salmivalli, Kaukiainen, Kaistaniemi, & Lagerspetz, 1999; Swearer & Espelage, 2011)
Sexual harassment could be viewed as a form of non-physical aggression on a continuum with sexual violence (Basile & Saltzman, 2002); thus, understanding correlates of sexual harassment victimization, and particularly perpetration, could be very important for sexual and dating violence prevention. A review of research shows estimated rates of sexual harassment among students to be between 23% and 87% (Attar-Schwartz, 2009; Fineran & Bennett, 1999; Harris & Associates, 1993; Hill et al., 2011; Langelan, 1993; Lipson & American Association of University Women Educational Foundation, 2001; Martin, 2008; McMaster, Connolly, Pepler, & Craig, 2002; Ormerod, Collinsworth, & Perry, 2008; Permanent Commission on the Status of Women [PCSW], 1995; Stein, Marshall, & Tropp 1993; Strauss & Espeland, 1992). Variance in rates may be attributed to differences in the methodology for identifying the sample, study power, and the operational definition of sexual harassment. In a small study of 21 female students attending an alternative high school, researchers found that 52% disclosed sexual harassment (Martin, 2008), whereas in a much larger study of 16,604 Israeli students in Grades 7 to 11, 26% reported at least one incident of sexual harassment (Attar-Schwartz, 2009). In a more recent study of students in Grades 7 to 12, approximately half (48%) experienced some form of sexual harassment in the 2010-2011 school year (Hill et al., 2011). Prior research indicated
Clear et al.
1205
that females were more likely than males to be sexually harassed (Hill et al., 2011; Lipson & American Association of University Women Educational Foundation, 2001; Ormerod et al., 2008; Sagrestano, 2009), and males were identified as perpetrators in more than 90% of the incidents of sexual harassment against females (Fineran & Bennett, 1999; Harris & Associates, 1993; Langelan, 1993; McMaster et al., 2002; PCSW, 1995; Robers, Zhang, Truman, Department of Justice, & National Center for Education Statistics, 2012; Stein et al., 1993; Strauss & Espeland, 1992). The limited research that has addressed the prevalence and health impact of sexual harassment victimization indicated that among adolescents, females were psychologically more affected by sexual harassment, had lower self-esteem, admitted to taking sexual harassment more personally, were victims of repeated sexual harassment, and were more likely to attempt suicide than males (Bagley, Bolitho, & Bertrand, 1997; Chiodo, Wolfe, Crooks, Hughes, & Jaffe, 2009; Gadin & Hammarstrom, 2005). Multiple studies have reported students feeling angry, upset, and threatened by sexual harassment, which contributed to lower self-esteem and confidence (Harris & Associates, 1993; PCSW, 1995; Stein et al., 1993; Strauss & Espeland, 1992). In addition to its effects on mental health, sexual harassment has consequences for students’ school performance, specifically poor grades, absenteeism, skipping or dropping classes, and poor school performance (Corbett & Gentry, 1993; Hand & Sanchez, 2000; Harris & Associates, 1993, 1993; Lee, Croninger, Linn, & Chen, 1996; Lipson & American Association of University Women Educational Foundation, 2001; Robers et al., 2012). Collectively, these findings indicate a need to more comprehensively document gender differences in sexual harassment victimization and perpetration and to identify other demographic or social factors associated with increased risk of sexual harassment. The purpose of the present study was to add to the limited research available on sexual harassment victimization and perpetration of high school students. We hypothesized that females reported higher rates of victimization, and males disclosed higher rates of perpetration. Rates of sexual harassment by tactic, direction, and sex were reported, including the co-occurrence of victimization and perpetration in the past 12 months. This research fills an important gap in the existing research by providing estimates of the frequency of sexual harassment victimization and perpetration among adolescents and by sex and other demographic and violence risk factors.
Method Participants All high school students (freshmen-seniors) attending 1 of 26 participating high schools and present during surveying were asked to complete a self-administered survey. The survey was a 95-item anonymous paper-and-pencil questionnaire that took approximately 25 to 40 min to complete. Between January and May 2010, study personnel traveled to the high schools and administered surveys either in a class administration setting in the school during a selected class (for example, English classes for
1206
Violence Against Women 20(10)
the whole day; n = 16), or a school group administration during which the whole school was surveyed in one class period (for example, first period; n = 10). The model for survey administration was familiar to schools, as it was used when conducting the Youth Risk Behavior Survey (YRBS; Centers for Disease Control and Prevention, 2009). All parents and guardians of enrolled students were mailed an informational letter describing the study purpose and the types of questions to be included on the survey. If parents or guardians did not wish for their student to participate in the survey, they were asked to call or email with the name and school of their student. So as not to single these students out from other classmates, study staff worked with the teachers to identify students whose parents did not wish for them to participate on the day of administration. Staff gave these students an identical survey booklet that did not contain any questions, but included the same face page and instructions as well as a Scantron® form. Students whose parents or guardians did not grant permission for them to participate were asked to bubble in the letter J for all answers on the Scantron® form so it would look as if they were participating. In the classroom, all students were asked not to write their name or birth date on the Scantron® forms. Elements of assent were read to all students by Collaborative Institutional Training Initiative trained staff. If the methodology was a school-wide one-period administration, a DVD with instructions was played for students. During the all-day administrations, study staff read the assent information to each class period. All students were directed to review the assent form in the survey booklet and decide for themselves whether they wished to complete the survey. Those opting not to complete the survey were asked to fill in the letter H on the Scantron® form and then quietly remain in their seat. All survey Scantron® forms were collected at the end of administration. Resources, including websites and toll-free numbers for national agencies available at all times to address domestic violence, sexual assaults, depression, or suicide ideation, were provided at the end of survey booklets. These resources were also given on pencils the students used to complete the survey and were able to keep. The national hotlines and websites linked individuals to local services. The study protocol was approved by the University of Kentucky Institutional Review Board 09-0680-F1V.
Measures Three items based on the Sexual Experiences Questionnaire (SEQ) were used to measure perpetration and victimization of sexual harassment (Fitzgerald, Magley, Drasgow, & Waldo, 1999). Items asked specifically about victimization and perpetration using the introduction of either, “In the past 12 months, how many times did another high school student . . .” or “In the past 12 months, how many times did YOU . . .” Items included the following: (a) Tell you sexual stories or jokes that made you uneasy? (b) Make gestures, rude remarks or use sexual body language to embarrass or upset you? (c) Keep asking you out on a date or asking you to hookup although you said “No”? Response options for all items ranged from never (0), 1 to 2 times (1), 3 to
Clear et al.
1207
5 times (2), 6 or more times (3). The response of yes, but not in the past 12 months was also an option but, for this analysis, we included it with never, because we were only interested in the past 12 months, not lifetime victimization or perpetration. Students who reported that any of the items occurred at least 3 or more times in the past 12 months were included in the sexual harassment definition. The Cronbach’s alpha coefficient for the three sexual harassment items indicated reasonable internal consistency for victimization (α = .66) and perpetration (α = .71). We investigated the co-occurrence of sexual harassment victimization and perpetration by specific sexual harassment tactics by gender. Demographic and other risk factors for sexual harassment were also evaluated. These included gender (female and male), high school grade (freshman, sophomore, junior, senior), race (categories summarized as non-White and White), receipt of a free or reduced price meal (yes or no, included as a proxy for family income), and sexual attraction (specifically, “People are different in their sexual attraction to other people. Which best describes your feelings?” Responses included only attracted to females, mostly attracted to females, equally attracted to females and males, mostly attracted to males, only attracted to males, and not sure). Responses were grouped as attracted to the opposite sex only versus attracted to the same or both sexes. The intraparental partner violence question was as follows: “In your family, how often did you see or hear one of your parents or guardians being hit, slapped, punched, shoved, kicked, or otherwise physically hurt by their spouse or partner?” Response options ranged from never to more than 10 times, but were dichotomized as yes or no. Questions regarding being bullied or having bullied others, respectively, were as follows: “In the past 12 months, how many times have you been bullied by another high school student?” and “In the past 12 months, how many times have you bullied another high school student?” Response options ranged from never to more than 10 times for both questions; we grouped answers as more than twice, 1 to 2 times, and never in the past 12 months. There was one question on binge drinking: “In the past month, on how many days did you have 4 (if you are a female) 5 (if you are a male) or more drinks of alcohol in a row (within a couple of hours)?” Response options ranged from I never drink to 20 to 31 days; a dichotomous variable was created to identify those students who reported binge drinking 1 or more days in the past 30, and at least 1 day in the past 30 days (yes vs. no).
Statistical Analysis All data were analyzed using SAS, Version 9.2. Because the purpose of this article is to document the rates of sexual harassment victimization and perpetration in this large high school population, adjusted rates are presented throughout Table 1 as well as Table 3. However, when investigating gender differences in rates, we adjusted odds ratios (aOR) for demographic factors known to be covariates, including age (freshman, sophomore, junior, or senior), family income (the proxy of receipt of a free or reduced price meal: yes or no), race (White or non-White), sexual attraction (exclusively attracted to the opposite sex or not), and a history of parental or guardian partner
1208
Violence Against Women 20(10)
violence (yes or no). In addition, these models were adjusted for the sampling design by blocking on the sampled high school (n = 26). Separate logistic regression models were used to estimate aORs by demographic correlates (chi-square test of proportions; presented in Table 1). Due to the large sample size of this study, only p values of
research-article2014
VAWXXX10.1177/1077801214551287Clear et al.Violence Against Women
Article
Sexual Harassment Victimization and Perpetration Among High School Students
Violence Against Women 2014, Vol. 20(10) 1203–1219 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1077801214551287 vaw.sagepub.com
Emily R. Clear1, Ann L. Coker1, Patricia G. Cook-Craig1, Heather M. Bush1, Lisandra S. Garcia1, Corrine M. Williams1, Alysha M. Lewis1, and Bonnie S. Fisher2
Abstract This large, population-based study is one of the few to examine prevalence rates of sexual harassment occurring during the past 12 months by victimization and perpetration among adolescents. In this large, cross-sectional survey of students attending 26 high schools, sexual harassment was defined using three questions from the Sexual Experiences Questionnaire. Among 18,090 students completing the survey, 30% disclosed sexual harassment victimization (37% of females, 21% of males) and 8.5% reported perpetration (5% of females, 12% of males). Sexual harassment perpetration was highly correlated with male sex, minority race/ethnicity, same-sex attraction, bullying, alcohol binge drinking, and intraparental partner violence. Keywords adolescents, high school, perpetration, sexual harassment, victimization Although sexual harassment has often been associated with the adult workplace environment, a shift toward exploring rates in high school-aged adolescents has emerged (Fineran & Bennett, 1999; Fineran & Bolen, 2006; Hill, Kearl, & American Association
1University 2University
of Kentucky, Lexington, KY, USA of Cincinnati, OH, USA
Corresponding Author: Emily R. Clear, Department of Obstetrics and Gynecology, A. B. Chandler Medical Center, University of Kentucky, 800 Rose Street, C347, Lexington, KY 40536-0293, USA. Email: [email protected]
1204
Violence Against Women 20(10)
of University Women, 2011). Sexual harassment as it relates to the school environment is defined as conduct that is sexual in nature, unwelcome, denies or limits a student’s ability to participate in or benefit from a school’s education program, and interferes with a student’s right to a supportive, respectful, and safe learning environment (U.S. Department of Education, Office for Civil Rights, 2008; Witkowska & Kjellberg, 2005). School-based definitions also address unwanted sexual behavior that interferes with a student’s educational opportunities, which may not be face-to-face, including cyberbullying through text messages and other social media (Hill et al., 2011). It is worth noting the difference between bullying and sexual harassment. Unlike bullying behaviors, sexual harassment incorporates a strong sexual component with little to no physical contact. Sexual harassment is an illegal form of sex discrimination that violates Title VII of the Civil Rights Act of 1964 (U.S. Equal Employment Opportunity Commission, 2009) and Title IX of the Education Amendments of 1972 (U.S. Department of Education, Office for Civil Rights, 1997). When bullying is used to describe sexual harassment, it takes away the role of gender and sex, which are key parts of the definition (Stein & Mennemeier, 2011). Nansel and colleagues used a definition that addressed the three components used in bullying definitions among researchers: Bullying is a specific type of aggression in which (1) the behavior is intended to harm or disturb, (2) the behavior occurs repeatedly over time, (3) there is an imbalance of power (physical or psychological), with a more powerful person or group attacking a less powerful one. (Nansel et al., 2001, p. 2094; Salmivalli, Kaukiainen, Kaistaniemi, & Lagerspetz, 1999; Swearer & Espelage, 2011)
Sexual harassment could be viewed as a form of non-physical aggression on a continuum with sexual violence (Basile & Saltzman, 2002); thus, understanding correlates of sexual harassment victimization, and particularly perpetration, could be very important for sexual and dating violence prevention. A review of research shows estimated rates of sexual harassment among students to be between 23% and 87% (Attar-Schwartz, 2009; Fineran & Bennett, 1999; Harris & Associates, 1993; Hill et al., 2011; Langelan, 1993; Lipson & American Association of University Women Educational Foundation, 2001; Martin, 2008; McMaster, Connolly, Pepler, & Craig, 2002; Ormerod, Collinsworth, & Perry, 2008; Permanent Commission on the Status of Women [PCSW], 1995; Stein, Marshall, & Tropp 1993; Strauss & Espeland, 1992). Variance in rates may be attributed to differences in the methodology for identifying the sample, study power, and the operational definition of sexual harassment. In a small study of 21 female students attending an alternative high school, researchers found that 52% disclosed sexual harassment (Martin, 2008), whereas in a much larger study of 16,604 Israeli students in Grades 7 to 11, 26% reported at least one incident of sexual harassment (Attar-Schwartz, 2009). In a more recent study of students in Grades 7 to 12, approximately half (48%) experienced some form of sexual harassment in the 2010-2011 school year (Hill et al., 2011). Prior research indicated
Clear et al.
1205
that females were more likely than males to be sexually harassed (Hill et al., 2011; Lipson & American Association of University Women Educational Foundation, 2001; Ormerod et al., 2008; Sagrestano, 2009), and males were identified as perpetrators in more than 90% of the incidents of sexual harassment against females (Fineran & Bennett, 1999; Harris & Associates, 1993; Langelan, 1993; McMaster et al., 2002; PCSW, 1995; Robers, Zhang, Truman, Department of Justice, & National Center for Education Statistics, 2012; Stein et al., 1993; Strauss & Espeland, 1992). The limited research that has addressed the prevalence and health impact of sexual harassment victimization indicated that among adolescents, females were psychologically more affected by sexual harassment, had lower self-esteem, admitted to taking sexual harassment more personally, were victims of repeated sexual harassment, and were more likely to attempt suicide than males (Bagley, Bolitho, & Bertrand, 1997; Chiodo, Wolfe, Crooks, Hughes, & Jaffe, 2009; Gadin & Hammarstrom, 2005). Multiple studies have reported students feeling angry, upset, and threatened by sexual harassment, which contributed to lower self-esteem and confidence (Harris & Associates, 1993; PCSW, 1995; Stein et al., 1993; Strauss & Espeland, 1992). In addition to its effects on mental health, sexual harassment has consequences for students’ school performance, specifically poor grades, absenteeism, skipping or dropping classes, and poor school performance (Corbett & Gentry, 1993; Hand & Sanchez, 2000; Harris & Associates, 1993, 1993; Lee, Croninger, Linn, & Chen, 1996; Lipson & American Association of University Women Educational Foundation, 2001; Robers et al., 2012). Collectively, these findings indicate a need to more comprehensively document gender differences in sexual harassment victimization and perpetration and to identify other demographic or social factors associated with increased risk of sexual harassment. The purpose of the present study was to add to the limited research available on sexual harassment victimization and perpetration of high school students. We hypothesized that females reported higher rates of victimization, and males disclosed higher rates of perpetration. Rates of sexual harassment by tactic, direction, and sex were reported, including the co-occurrence of victimization and perpetration in the past 12 months. This research fills an important gap in the existing research by providing estimates of the frequency of sexual harassment victimization and perpetration among adolescents and by sex and other demographic and violence risk factors.
Method Participants All high school students (freshmen-seniors) attending 1 of 26 participating high schools and present during surveying were asked to complete a self-administered survey. The survey was a 95-item anonymous paper-and-pencil questionnaire that took approximately 25 to 40 min to complete. Between January and May 2010, study personnel traveled to the high schools and administered surveys either in a class administration setting in the school during a selected class (for example, English classes for
1206
Violence Against Women 20(10)
the whole day; n = 16), or a school group administration during which the whole school was surveyed in one class period (for example, first period; n = 10). The model for survey administration was familiar to schools, as it was used when conducting the Youth Risk Behavior Survey (YRBS; Centers for Disease Control and Prevention, 2009). All parents and guardians of enrolled students were mailed an informational letter describing the study purpose and the types of questions to be included on the survey. If parents or guardians did not wish for their student to participate in the survey, they were asked to call or email with the name and school of their student. So as not to single these students out from other classmates, study staff worked with the teachers to identify students whose parents did not wish for them to participate on the day of administration. Staff gave these students an identical survey booklet that did not contain any questions, but included the same face page and instructions as well as a Scantron® form. Students whose parents or guardians did not grant permission for them to participate were asked to bubble in the letter J for all answers on the Scantron® form so it would look as if they were participating. In the classroom, all students were asked not to write their name or birth date on the Scantron® forms. Elements of assent were read to all students by Collaborative Institutional Training Initiative trained staff. If the methodology was a school-wide one-period administration, a DVD with instructions was played for students. During the all-day administrations, study staff read the assent information to each class period. All students were directed to review the assent form in the survey booklet and decide for themselves whether they wished to complete the survey. Those opting not to complete the survey were asked to fill in the letter H on the Scantron® form and then quietly remain in their seat. All survey Scantron® forms were collected at the end of administration. Resources, including websites and toll-free numbers for national agencies available at all times to address domestic violence, sexual assaults, depression, or suicide ideation, were provided at the end of survey booklets. These resources were also given on pencils the students used to complete the survey and were able to keep. The national hotlines and websites linked individuals to local services. The study protocol was approved by the University of Kentucky Institutional Review Board 09-0680-F1V.
Measures Three items based on the Sexual Experiences Questionnaire (SEQ) were used to measure perpetration and victimization of sexual harassment (Fitzgerald, Magley, Drasgow, & Waldo, 1999). Items asked specifically about victimization and perpetration using the introduction of either, “In the past 12 months, how many times did another high school student . . .” or “In the past 12 months, how many times did YOU . . .” Items included the following: (a) Tell you sexual stories or jokes that made you uneasy? (b) Make gestures, rude remarks or use sexual body language to embarrass or upset you? (c) Keep asking you out on a date or asking you to hookup although you said “No”? Response options for all items ranged from never (0), 1 to 2 times (1), 3 to
Clear et al.
1207
5 times (2), 6 or more times (3). The response of yes, but not in the past 12 months was also an option but, for this analysis, we included it with never, because we were only interested in the past 12 months, not lifetime victimization or perpetration. Students who reported that any of the items occurred at least 3 or more times in the past 12 months were included in the sexual harassment definition. The Cronbach’s alpha coefficient for the three sexual harassment items indicated reasonable internal consistency for victimization (α = .66) and perpetration (α = .71). We investigated the co-occurrence of sexual harassment victimization and perpetration by specific sexual harassment tactics by gender. Demographic and other risk factors for sexual harassment were also evaluated. These included gender (female and male), high school grade (freshman, sophomore, junior, senior), race (categories summarized as non-White and White), receipt of a free or reduced price meal (yes or no, included as a proxy for family income), and sexual attraction (specifically, “People are different in their sexual attraction to other people. Which best describes your feelings?” Responses included only attracted to females, mostly attracted to females, equally attracted to females and males, mostly attracted to males, only attracted to males, and not sure). Responses were grouped as attracted to the opposite sex only versus attracted to the same or both sexes. The intraparental partner violence question was as follows: “In your family, how often did you see or hear one of your parents or guardians being hit, slapped, punched, shoved, kicked, or otherwise physically hurt by their spouse or partner?” Response options ranged from never to more than 10 times, but were dichotomized as yes or no. Questions regarding being bullied or having bullied others, respectively, were as follows: “In the past 12 months, how many times have you been bullied by another high school student?” and “In the past 12 months, how many times have you bullied another high school student?” Response options ranged from never to more than 10 times for both questions; we grouped answers as more than twice, 1 to 2 times, and never in the past 12 months. There was one question on binge drinking: “In the past month, on how many days did you have 4 (if you are a female) 5 (if you are a male) or more drinks of alcohol in a row (within a couple of hours)?” Response options ranged from I never drink to 20 to 31 days; a dichotomous variable was created to identify those students who reported binge drinking 1 or more days in the past 30, and at least 1 day in the past 30 days (yes vs. no).
Statistical Analysis All data were analyzed using SAS, Version 9.2. Because the purpose of this article is to document the rates of sexual harassment victimization and perpetration in this large high school population, adjusted rates are presented throughout Table 1 as well as Table 3. However, when investigating gender differences in rates, we adjusted odds ratios (aOR) for demographic factors known to be covariates, including age (freshman, sophomore, junior, or senior), family income (the proxy of receipt of a free or reduced price meal: yes or no), race (White or non-White), sexual attraction (exclusively attracted to the opposite sex or not), and a history of parental or guardian partner
1208
Violence Against Women 20(10)
violence (yes or no). In addition, these models were adjusted for the sampling design by blocking on the sampled high school (n = 26). Separate logistic regression models were used to estimate aORs by demographic correlates (chi-square test of proportions; presented in Table 1). Due to the large sample size of this study, only p values of
