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, demographicopportunity 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