《性别、亲密关系与社会》课程教学资源（计划生育）MATE AVAILABILITY AND WOMEN'S SEXUAL EXPERIENCES IN CHINA

MATE AVAILABILITY AND WOMEN'S SEXUAL EXPERIENCES IN CHINA* Katherine Trent Department of Sociology Center for Social and Demographic Analysis University at Albany State University of New York Albany,NY 12222 Phone:518-442-4681 E-mail:k.trent@albany.edu Fax:518-442-4936 Scott J.South Department of Sociology Center for Social and Demographic Analysis University at Albany State University of New York Albany,NY 12222 Phone:518-442-4691 E-mail:s.south@albany.edu Fax:518-442-4936 November 2010 Word count:7493 Number of Tables:2 Running Head:Mate Availability and Women's Sexual Experiences *Direct correspondence to Katherine Trent,Department of Sociology,University at Albany, SUNY,Albany,NY 12222.E-mail:k.trent@albany.edu.We thank Yong Cai,Baochang Gu, Lin Guo,Zai Liang,Jeremy Pais,William Parish,Kelly McGeever,and Carey Sojka for helpful assistance.This research was supported by a grant to the authors from the National Institute of Child Health and Human Development(R21 HD057289).The Center for Social and Demographic Analysis of the University at Albany provided technical and administrative support for this research through a grant from NICHD (R24 HD044943)

MATE AVAILABILITY AND WOMEN'S SEXUAL EXPERIENCES IN CHINA* Katherine Trent Department of Sociology Center for Social and Demographic Analysis University at Albany State University of New York Albany, NY 12222 Phone: 518-442-4681 E-mail: k.trent@albany.edu Fax: 518-442-4936 Scott J. South Department of Sociology Center for Social and Demographic Analysis University at Albany State University of New York Albany, NY 12222 Phone: 518-442-4691 E-mail: s.south@albany.edu Fax: 518-442-4936 November 2010 Word count: 7493 Number of Tables: 2 Running Head: Mate Availability and Women’s Sexual Experiences *Direct correspondence to Katherine Trent, Department of Sociology, University at Albany, SUNY, Albany, NY 12222. E-mail: k.trent@albany.edu. We thank Yong Cai, Baochang Gu, Lin Guo, Zai Liang, Jeremy Pais, William Parish, Kelly McGeever, and Carey Sojka for helpful assistance. This research was supported by a grant to the authors from the National Institute of Child Health and Human Development (R21 HD057289). The Center for Social and Demographic Analysis of the University at Albany provided technical and administrative support for this research through a grant from NICHD (R24 HD044943)

MATE AVAILABILITY AND WOMEN'S SEXUAL EXPERIENCES IN CHINA Abstract We use data from the 1999-2000 Chinese Health and Family Life Survey merged with community-level data from the 1982,1990,and 2000 Chinese censuses to examine the relationship between the local sex ratio(number of men per 100 women)and sexual outcomes among women.Consistent with hypotheses derived from demographic-opportunity theory, logistic regression analyses show that women are more likely to have had recent and nonmarital sexual intercourse,to have been forced to have sex,and to test positive for a sexually-transmitted infection when there is a relative abundance of age-matched men in their local community. Education,birth cohort,and geographic location also emerge as significant predictors of women's sexual experiences

MATE AVAILABILITY AND WOMEN'S SEXUAL EXPERIENCES IN CHINA Abstract We use data from the 1999-2000 Chinese Health and Family Life Survey merged with community-level data from the 1982, 1990, and 2000 Chinese censuses to examine the relationship between the local sex ratio (number of men per 100 women) and sexual outcomes among women. Consistent with hypotheses derived from demographic-opportunity theory, logistic regression analyses show that women are more likely to have had recent and nonmarital sexual intercourse, to have been forced to have sex, and to test positive for a sexually-transmitted infection when there is a relative abundance of age-matched men in their local community. Education, birth cohort, and geographic location also emerge as significant predictors of women’s sexual experiences

MATE AVAILABILITY AND WOMEN'S SEXUAL EXPERIENCES IN CHINA The relative number of young men and women in the People's Republic of China has undergone remarkable change over recent decades.China's one-child policy,precipitous declines in fertility,a cultural preference for sons,and sex-selective abortion,have led to a surplus of men in recent decades(Banister 2004;Goodkind 2004).Many scholars have pointed to an unusually high sex ratio at birth in China(e.g.,Cai and Lavely 2003;Coale and Banister 1994;Gu and Roy 1995;Hull 1990;Johansson and Nygren 1991;Lavely 2001;Murphy 2003;Peng and Huang 1999;Secondi 2002;Yi et al.1993:Yuan and Tu 2004).A normal range of the sex ratio at birth (number of males per 100 females)is considered to be between 103 and 107.In 1982,China's sex ratio at birth-between 107 and 108-was already at the high end of this range,and it has increased dramatically since that time.By 1990 the sex ratio at birth had grown to 111.3,by 2001 it was 118(Poston and Glover 2005),and by 2005 it had reached 120.5(Li 2007) Given these changes in the sex ratio at birth,China is expected to experience a pronounced surplus of adult men relative to adult women as these birth cohorts age(Tuljapurkar, Li,and Feldman 1995).Some observers suggest that this increasing population of excess men will have far-reaching social and demographic consequences,contributing to the spread of HIV and other sexually transmitted infections(STIs).Poston and Glover(2005)suggest that an increase in commercial sex will hasten the spread of HIV/AIDS.Tucker and colleagues(2005; see also Ebenstein and Jennings 2009)speculate that other high sexual risk behaviors among surplus men will facilitate transmission of HIV/AIDS and other STIs throughout the population. However,there is little systematic empirical research on how imbalanced sex ratios influence sexual behaviors in China or in other populations.In this paper,we examine the effect of imbalanced sex ratios on several aspects of Chinese women's sexual experiences.Given 1

1 MATE AVAILABILITY AND WOMEN'S SEXUAL EXPERIENCES IN CHINA The relative number of young men and women in the People’s Republic of China has undergone remarkable change over recent decades. China’s one-child policy, precipitous declines in fertility, a cultural preference for sons, and sex-selective abortion, have led to a surplus of men in recent decades (Banister 2004; Goodkind 2004). Many scholars have pointed to an unusually high sex ratio at birth in China (e.g., Cai and Lavely 2003; Coale and Banister 1994; Gu and Roy 1995; Hull 1990; Johansson and Nygren 1991; Lavely 2001; Murphy 2003; Peng and Huang 1999; Secondi 2002; Yi et al. 1993; Yuan and Tu 2004). A normal range of the sex ratio at birth (number of males per 100 females) is considered to be between 103 and 107. In 1982, China’s sex ratio at birth—between 107 and 108—was already at the high end of this range, and it has increased dramatically since that time. By 1990 the sex ratio at birth had grown to 111.3, by 2001 it was 118 (Poston and Glover 2005), and by 2005 it had reached 120.5 (Li 2007). Given these changes in the sex ratio at birth, China is expected to experience a pronounced surplus of adult men relative to adult women as these birth cohorts age (Tuljapurkar, Li, and Feldman 1995). Some observers suggest that this increasing population of excess men will have far-reaching social and demographic consequences, contributing to the spread of HIV and other sexually transmitted infections (STIs). Poston and Glover (2005) suggest that an increase in commercial sex will hasten the spread of HIV/AIDS. Tucker and colleagues (2005; see also Ebenstein and Jennings 2009) speculate that other high sexual risk behaviors among surplus men will facilitate transmission of HIV/AIDS and other STIs throughout the population. However, there is little systematic empirical research on how imbalanced sex ratios influence sexual behaviors in China or in other populations. In this paper, we examine the effect of imbalanced sex ratios on several aspects of Chinese women’s sexual experiences. Given

recent changes and substantial inter-community variation in its sex ratio,China represents an opportune case for examining the impact of imbalanced sex ratios on women's sexual outcomes. Our conceptual framework is grounded in demographic-opportunity theory,which broadly suggests that a surplus of men will shape both the frequency and form of women's sexual encounters.We test hypotheses derived from this theory using individual-level data from the Chinese Health and Family Life Survey(CHFLS)merged with community-level data taken from three Chinese censuses.From the Chinese censuses we create cohort-specific and community- specific sex ratios describing the number of men available to women,and we then attach these sex ratios to the individual records of the female respondents to the CHFLS.We then estimate logistic regression models linking four outcomes-whether women have engaged in recent sexual intercourse,have been victims of forced sex,have had nonmarital sex,and whether they test positive for an STI-to the sex ratio in their local community. THEORETICAL BACKGROUND AND HYPOTHESES A common theoretical framework from which to address the effect of imbalanced sex ratios on sexual and familial behavior is demographic-opportunity theory(South,Trent,and Shen 2001;Uecker and Regnerus 2010).Demographic-opportunity considers the distribution of the population by sex,as well as by other critical sociodemographic characteristics such as age and race,to be a defining characteristic of social structure(Blau 1977).A fundamental premise of demographic-opportunity theory is that the likelihood of social contact between people with different demographic attributes-for example,between women and men-is determined in part by the number of available out-group members with whom such contacts could occur.Thus, demographic-opportunity theory emphasizes how the sheer number of men available to women shapes the frequency and form of women's sexual encounters.When applied to women's sexual 2

2 recent changes and substantial inter-community variation in its sex ratio, China represents an opportune case for examining the impact of imbalanced sex ratios on women’s sexual outcomes. Our conceptual framework is grounded in demographic-opportunity theory, which broadly suggests that a surplus of men will shape both the frequency and form of women’s sexual encounters. We test hypotheses derived from this theory using individual-level data from the Chinese Health and Family Life Survey (CHFLS) merged with community-level data taken from three Chinese censuses. From the Chinese censuses we create cohort-specific and community￾specific sex ratios describing the number of men available to women, and we then attach these sex ratios to the individual records of the female respondents to the CHFLS. We then estimate logistic regression models linking four outcomes—whether women have engaged in recent sexual intercourse, have been victims of forced sex, have had nonmarital sex, and whether they test positive for an STI—to the sex ratio in their local community. THEORETICAL BACKGROUND AND HYPOTHESES A common theoretical framework from which to address the effect of imbalanced sex ratios on sexual and familial behavior is demographic-opportunity theory (South, Trent, and Shen 2001; Uecker and Regnerus 2010). Demographic-opportunity considers the distribution of the population by sex, as well as by other critical sociodemographic characteristics such as age and race, to be a defining characteristic of social structure (Blau 1977). A fundamental premise of demographic-opportunity theory is that the likelihood of social contact between people with different demographic attributes—for example, between women and men—is determined in part by the number of available out-group members with whom such contacts could occur. Thus, demographic-opportunity theory emphasizes how the sheer number of men available to women shapes the frequency and form of women’s sexual encounters. When applied to women’s sexual

experiences,demographic-opportunity theory suggests that the probability of engaging in recent or nonmarital sexual intercourse,of being the victim of forced sex,and of testing positive for a STI increases along with the number of men in the local population. Prior tests of demographic-opportunity theory have focused primarily on how imbalanced sex ratios affect marital and familial behavior in the United States.We know that women's marriage rates are higher in geographic areas containing more eligible and economically attractive men (e.g.,Fossett and Kiecolt 1993;Lichter et al.1992;McLaughlin,Lichter,and Johnston 1993).A surplus of men has also been linked to young women's chances of"marrying up"educationally,although there is little evidence that sex ratios affect educational or occupational marital heterogamy (Lichter,Anderson,and Hayward 1995). High sex ratios,indicating an excess of men relative to women,are also associated with an increase in women's risk of nonmarital childbearing (Billy and Moore 1992;South and Lloyd 1992).Ostensibly,a numerical surplus of men increases young women's risk of unmarried childbearing by increasing the likelihood that they will engage in premarital intercourse,although this association is likely tempered by an accompanying risk of early marriage(South 1996) Similar findings have been observed in cross-national studies(Barber 2001;2004;South and Trent 1988).Imbalanced sex ratios have also been linked to marital dissolution and relationship quality.A surplus of women lowers relationship quality among unmarried parents(Harknett 2008),though not among married persons more generally(Trent and South 2003).Several studies suggest that married couples who are exposed to either a surplus of men or women are more likely to divorce,presumably because in these demographic contexts spouses are especially likely to encounter an attractive alternative to their current partner(McKinnish 2004;South, Trent,and Shen 2001). 3

3 experiences, demographic-opportunity theory suggests that the probability of engaging in recent or nonmarital sexual intercourse, of being the victim of forced sex, and of testing positive for a STI increases along with the number of men in the local population. Prior tests of demographic-opportunity theory have focused primarily on how imbalanced sex ratios affect marital and familial behavior in the United States. We know that women’s marriage rates are higher in geographic areas containing more eligible and economically attractive men (e.g., Fossett and Kiecolt 1993; Lichter et al. 1992; McLaughlin, Lichter, and Johnston 1993). A surplus of men has also been linked to young women’s chances of ―marrying up‖ educationally, although there is little evidence that sex ratios affect educational or occupational marital heterogamy (Lichter, Anderson, and Hayward 1995). High sex ratios, indicating an excess of men relative to women, are also associated with an increase in women’s risk of nonmarital childbearing (Billy and Moore 1992; South and Lloyd 1992). Ostensibly, a numerical surplus of men increases young women’s risk of unmarried childbearing by increasing the likelihood that they will engage in premarital intercourse, although this association is likely tempered by an accompanying risk of early marriage (South 1996). Similar findings have been observed in cross-national studies (Barber 2001; 2004; South and Trent 1988). Imbalanced sex ratios have also been linked to marital dissolution and relationship quality. A surplus of women lowers relationship quality among unmarried parents (Harknett 2008), though not among married persons more generally (Trent and South 2003). Several studies suggest that married couples who are exposed to either a surplus of men or women are more likely to divorce, presumably because in these demographic contexts spouses are especially likely to encounter an attractive alternative to their current partner (McKinnish 2004; South, Trent, and Shen 2001)

The literature is sparser and less consistent regarding the influence of mate availability on sexual behavior.Consistent with demographic-opportunity theory,Billy,Brewster,and Grady (1994)find a positive association in the U.S.between the county-level sex ratio and young women's risk of engaging in premarital intercourse and the frequency with which they engage in intercourse.However,Brewster(1994)does not observe a significant association between the neighborhood-level sex ratio and the timing of young black women's transition to first sexual activity.And,contrary to the predictions of demographic-opportunity theory,Uecker and Regnerus(2010)find that young women are more likely to engage in sex when they attend college with comparatively few men.Browning and Olinger-Wilbon(2003)find that men engage in more short-term sexual alliances in neighborhoods that contain comparatively few women. Imbalanced sex ratios have also been linked to the frequency of violence-and particularly sexual violence--against women.Although the literature is not entirely consistent (O'Brien 1991;Whaley 2001),several studies have shown that,within the U.S.,rape victimization rates are higher in areas characterized by a surplus of men and an attendant deficit of women (Blau and Golden 1986;Messner and Blau 1987).In addition,the sex ratio is positively associated with female homicide victimization (Avakame 1999)and male-on-female intimate partner violence(D'Alessio and Stolzenberg 2010).Presumably,when women are scarce men lack the ability to form conventional sexual relationships and thus resort to violence to satisfy their sexual needs and maintain control over actual or potential mates.More generally, China's increasingly masculine sex ratio has been argued to be a partial cause of its increasing rate of crime (Edlund et al.2007). 4

4 The literature is sparser and less consistent regarding the influence of mate availability on sexual behavior. Consistent with demographic-opportunity theory, Billy, Brewster, and Grady (1994) find a positive association in the U. S. between the county-level sex ratio and young women’s risk of engaging in premarital intercourse and the frequency with which they engage in intercourse. However, Brewster (1994) does not observe a significant association between the neighborhood-level sex ratio and the timing of young black women’s transition to first sexual activity. And, contrary to the predictions of demographic-opportunity theory, Uecker and Regnerus (2010) find that young women are more likely to engage in sex when they attend college with comparatively few men. Browning and Olinger-Wilbon (2003) find that men engage in more short-term sexual alliances in neighborhoods that contain comparatively few women. Imbalanced sex ratios have also been linked to the frequency of violence—and particularly sexual violence--against women. Although the literature is not entirely consistent (O’Brien 1991; Whaley 2001), several studies have shown that, within the U. S., rape victimization rates are higher in areas characterized by a surplus of men and an attendant deficit of women (Blau and Golden 1986; Messner and Blau 1987). In addition, the sex ratio is positively associated with female homicide victimization (Avakame 1999) and male-on-female intimate partner violence (D’Alessio and Stolzenberg 2010). Presumably, when women are scarce men lack the ability to form conventional sexual relationships and thus resort to violence to satisfy their sexual needs and maintain control over actual or potential mates. More generally, China’s increasingly masculine sex ratio has been argued to be a partial cause of its increasing rate of crime (Edlund et al. 2007)

Hypotheses Demographic-opportunity theory implies several hypotheses regarding the impact of the local sex ratio on the nature and consequences of women's sexual encounters.First, demographic-opportunity theory predicts that,when faced with a relative surplus of men,women will be more likely to engage in sexual intercourse.A relative abundance of men increases the likelihood that women will encounter an attractive sexual partner,particularly though not exclusively through marriage,thereby increasing their chances of engaging in sexual intercourse. In contrast,when men are scarce,women's opportunities to attract a sexual partner will be more limited,and hence women will engage less frequently in sexual intercourse.Thus,demographic- opportunity theory predicts a positive association between the local sex ratio and women's chances of having recently engaged in sexual intercourse. Second,demographic-opportunity theory implies that women will be more likely to be forced to engage in sexual intercourse when they are exposed to a numerical surplus of men. When women are in short supply,many men in women's pool of eligibles will be unable to find sexual and marital partners through more conventional,socially-sanctioned means.Instead,these men will turn to illicit or criminal behavior such as visiting commercial sex workers or obtaining sex through physical force.A numerical deficit of women may also mean that women will be isolated from other women and thus more vulnerable to violence perpetrated by sexually aggressive men.Even among married persons,a numerical surplus of men-and accompanying deficit of women-may spur sexual violence by husbands,both because men will have few sexual opportunities outside of marriage and as a means of preventing women from exploiting the extramarital opportunities available to them (D'Alessio and Stolzenberg 2010).For all these 5

5 Hypotheses Demographic-opportunity theory implies several hypotheses regarding the impact of the local sex ratio on the nature and consequences of women’s sexual encounters. First, demographic-opportunity theory predicts that, when faced with a relative surplus of men, women will be more likely to engage in sexual intercourse. A relative abundance of men increases the likelihood that women will encounter an attractive sexual partner, particularly though not exclusively through marriage, thereby increasing their chances of engaging in sexual intercourse. In contrast, when men are scarce, women’s opportunities to attract a sexual partner will be more limited, and hence women will engage less frequently in sexual intercourse. Thus, demographic￾opportunity theory predicts a positive association between the local sex ratio and women’s chances of having recently engaged in sexual intercourse. Second, demographic-opportunity theory implies that women will be more likely to be forced to engage in sexual intercourse when they are exposed to a numerical surplus of men. When women are in short supply, many men in women’s pool of eligibles will be unable to find sexual and marital partners through more conventional, socially-sanctioned means. Instead, these men will turn to illicit or criminal behavior such as visiting commercial sex workers or obtaining sex through physical force. A numerical deficit of women may also mean that women will be isolated from other women and thus more vulnerable to violence perpetrated by sexually aggressive men. Even among married persons, a numerical surplus of men—and accompanying deficit of women—may spur sexual violence by husbands, both because men will have few sexual opportunities outside of marriage and as a means of preventing women from exploiting the extramarital opportunities available to them (D’Alessio and Stolzenberg 2010). For all these

reasons,demographic-opportunity theory predicts a positive association between the community sex ratio and women's likelihood of being victims of forced sexual intercourse. A third hypothesis implied by demographic-opportunity theory is that women's likelihood of engaging in nonmarital sexual intercourse is greater in communities containing relatively large numbers of men.A numerical surplus of men increases the chances that women will encounter an attractive sexual partner both prior to marrying and,once married,outside of the marital relationship.Moreover,although divorce is fairly rare in China,a surplus of men may also increase women's risk of divorcing and thus the duration of time women spend unmarried and hence at higher risk of engaging in nonmarital sexual intercourse.To be sure,there may be countervailing forces at work here,because an abundance of men may also increase the chances that women will meet a potential husband early in life,and marrying young limits the amount of time that women are exposed to the risk of having sexual intercourse prior to marriage.However, most Chinese women marry late in life (Sheng 2005),so it is likely that this offsetting influence will be minimal. Finally,we extend demographic-opportunity theory to hypothesize that a numerical surplus of men will increase the risk that women will contract a sexually transmitted infection (STI).A surplus of men is likely to increase women's chances of contracting an STI through several pathways.First,a male surplus is likely to increase the sheer frequency with which women engage in sexual intercourse;in turn,and all else equal,more frequent intercourse increases the risk of contracting a sexually-transmitted infection.Moreover,a surplus of men likely influences the nature of women's sexual encounters beyond the frequency of intercourse. As argued above,a surplus of men is likely to increase women's risk of engaging in sexual intercourse outside of marriage and presumably with more lifetime partners.In addition,a surfeit 6

6 reasons, demographic-opportunity theory predicts a positive association between the community sex ratio and women’s likelihood of being victims of forced sexual intercourse. A third hypothesis implied by demographic-opportunity theory is that women’s likelihood of engaging in nonmarital sexual intercourse is greater in communities containing relatively large numbers of men. A numerical surplus of men increases the chances that women will encounter an attractive sexual partner both prior to marrying and, once married, outside of the marital relationship. Moreover, although divorce is fairly rare in China, a surplus of men may also increase women’s risk of divorcing and thus the duration of time women spend unmarried and hence at higher risk of engaging in nonmarital sexual intercourse. To be sure, there may be countervailing forces at work here, because an abundance of men may also increase the chances that women will meet a potential husband early in life, and marrying young limits the amount of time that women are exposed to the risk of having sexual intercourse prior to marriage. However, most Chinese women marry late in life (Sheng 2005), so it is likely that this offsetting influence will be minimal. Finally, we extend demographic-opportunity theory to hypothesize that a numerical surplus of men will increase the risk that women will contract a sexually transmitted infection (STI). A surplus of men is likely to increase women’s chances of contracting an STI through several pathways. First, a male surplus is likely to increase the sheer frequency with which women engage in sexual intercourse; in turn, and all else equal, more frequent intercourse increases the risk of contracting a sexually-transmitted infection. Moreover, a surplus of men likely influences the nature of women’s sexual encounters beyond the frequency of intercourse. As argued above, a surplus of men is likely to increase women’s risk of engaging in sexual intercourse outside of marriage and presumably with more lifetime partners. In addition, a surfeit

of men and concomitant shortage of women may also increase women's risk of being forced to have sexual intercourse and of engaging in sex with a partner who has visited commercial sex workers.All of these are risk factors for contracting an STL,including HIV/AIDS(Gil et al. 1996;Merli et al.2006;Tucker,Ren,and Sapio 2010;Xiao et al.2007).In contrast,when men are relatively scarce,women will have fewer opportunities to engage in sexual intercourse(or have intercourse forced upon them),so they will do so less frequently and with fewer different partners,thereby diminishing their risk of contracting an STI. DATA AND METHODS We test the hypotheses developed above using data from the Chinese Health and Family Life Survey(CHFLS)in conjunction with community-level data from three Chinese censuses. The CHFLS is a nationally-representative survey (with the exception of Hong Kong and Tibet)of 3,821 Chinese adults ages 20 to 64(Chinese Health and Family Life Survey 2006).The CHFLS was administered between August 1999 and August 2000.Modeled in large part on the U.S National Health and Social Life Survey (Laumann et al.1994),the CHFLS focuses on sexual and family-related behaviors and attitudes (Parish et al.2003). For this analysis we select female CHFLS respondents between the ages of 20 and 44.We focus on this age range partly because women older than 44 are not likely to have experienced the numerical surplus of men experienced by younger cohorts.Moreover,our measurement strategy requires that we estimate the relative numbers of men"available"to these women when they were age 20.The earliest available China census containing the requisite information is for 1982,and thus it is not possible to estimate with confidence the community-and cohort-specific sex ratio for women who are older than 44 at the date of the CHFLS administration

7 of men and concomitant shortage of women may also increase women’s risk of being forced to have sexual intercourse and of engaging in sex with a partner who has visited commercial sex workers. All of these are risk factors for contracting an STI, including HIV/AIDS (Gil et al. 1996; Merli et al. 2006; Tucker, Ren, and Sapio 2010; Xiao et al. 2007). In contrast, when men are relatively scarce, women will have fewer opportunities to engage in sexual intercourse (or have intercourse forced upon them), so they will do so less frequently and with fewer different partners, thereby diminishing their risk of contracting an STI. DATA AND METHODS We test the hypotheses developed above using data from the Chinese Health and Family Life Survey (CHFLS) in conjunction with community-level data from three Chinese censuses. The CHFLS is a nationally-representative survey (with the exception of Hong Kong and Tibet) of 3,821 Chinese adults ages 20 to 64 (Chinese Health and Family Life Survey 2006). The CHFLS was administered between August 1999 and August 2000. Modeled in large part on the U.S. National Health and Social Life Survey (Laumann et al. 1994), the CHFLS focuses on sexual and family-related behaviors and attitudes (Parish et al. 2003). For this analysis we select female CHFLS respondents between the ages of 20 and 44. We focus on this age range partly because women older than 44 are not likely to have experienced the numerical surplus of men experienced by younger cohorts. Moreover, our measurement strategy requires that we estimate the relative numbers of men "available" to these women when they were age 20. The earliest available China census containing the requisite information is for 1982, and thus it is not possible to estimate with confidence the community- and cohort-specific sex ratio for women who are older than 44 at the date of the CHFLS administration

Dependent Variables:We examine the impact of the relative number of men available to the women CHFLS respondents on four dimensions of women's sexual encounters and their outcomes.All of these variables are dichotomous.Recent sex is a dichotomous variable scored 1 if the respondent reports having had sexual intercourse in the past year.Forced sex is a dichotomous variable scored 1 if the respondent reports ever having been forced to have sex against her will.Nonmarital sex is a dichotomous variable scored 1 for respondents who report having had sexual intercourse outside of marriage,i.e.,either prior to marrying or,while married, with someone other than their husband.Finally,the CHFLS respondents were asked to provide a urine sample to be tested for the presence of gonorrhea,chlamydia,and trichomonas infections. Over 90%of the respondents provided a urine sample.The fourth dependent variable (Has STI) is a dichotomous variable scored 1 for respondents who tested positive for gonorrheal, chlamydial,or trichomoniasis infection. Independent Variables:Our focal independent variable is the sex ratio,expressed here as the number of men per 100 women.The relevant pool of men available to serve as sexual partners for women is of course circumscribed both by geography and by age.To circumscribe these pools of eligible mates geographically,we have coded the county or county-equivalent (e.g., urban district,county-level city)for each of the CHFLS respondents.For county-level cities that are under prefecture-level cities and shixiagu,we use data for the entire prefecture-level city (essentially a large city or metropolitan area).For county-level cities that are under the province and for non-city counties,we use data at the county level.These geographic approximations of community correspond to the spatially-defined marriage markets(e.g.,metropolitan areas,labor market areas,or nonmetropolitan counties)used in much U.S.research on the impact of 8

8 Dependent Variables: We examine the impact of the relative number of men available to the women CHFLS respondents on four dimensions of women’s sexual encounters and their outcomes. All of these variables are dichotomous. Recent sex is a dichotomous variable scored 1 if the respondent reports having had sexual intercourse in the past year. Forced sex is a dichotomous variable scored 1 if the respondent reports ever having been forced to have sex against her will. Nonmarital sex is a dichotomous variable scored 1 for respondents who report having had sexual intercourse outside of marriage, i.e., either prior to marrying or, while married, with someone other than their husband. Finally, the CHFLS respondents were asked to provide a urine sample to be tested for the presence of gonorrhea, chlamydia, and trichomonas infections. Over 90% of the respondents provided a urine sample. The fourth dependent variable (Has STI) is a dichotomous variable scored 1 for respondents who tested positive for gonorrheal, chlamydial, or trichomoniasis infection.1 Independent Variables: Our focal independent variable is the sex ratio, expressed here as the number of men per 100 women. The relevant pool of men available to serve as sexual partners for women is of course circumscribed both by geography and by age. To circumscribe these pools of eligible mates geographically, we have coded the county or county-equivalent (e.g., urban district, county-level city) for each of the CHFLS respondents. For county-level cities that are under prefecture-level cities and shixiaqu, we use data for the entire prefecture-level city (essentially a large city or metropolitan area). For county-level cities that are under the province and for non-city counties, we use data at the county level. These geographic approximations of community correspond to the spatially-defined marriage markets (e.g., metropolitan areas, labor market areas, or nonmetropolitan counties) used in much U.S. research on the impact of