Sandra L Martin

University of North Carolina at Chapel Hill, Chapel Hill, NC, United States

Are you Sandra L Martin?

Claim your profile

Publications (70)227.33 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Population sexual mixing patterns can be quantified using Newman's assortativity coefficient (r). Suggested methods for estimating the SE for r may lead to inappropriate statistical conclusions in situations where intracluster correlation is ignored and/or when cluster size is predictive of the response. We describe a computer-intensive, but highly accessible, within-cluster resampling approach for providing a valid large-sample estimated SE for r and an associated 95% CI. We introduce needed statistical notation and describe the within-cluster resampling approach. Sexual network data and a simulation study were employed to compare within-cluster resampling with standard methods when cluster size is informative. For the analysis of network data when cluster size is informative, the simulation study demonstrates that within-cluster resampling produces valid statistical inferences about Newman's assortativity coefficient, a popular statistic used to quantify the strength of mixing patterns. In contrast, commonly used methods are biased with attendant extremely poor CI coverage. Within-cluster resampling is recommended when cluster size is informative and/or when there is within-cluster response correlation. Within-cluster resampling is recommended for providing valid statistical inferences when applying Newman's assortativity coefficient r to network data.
    Sexually transmitted infections 01/2014; · 2.18 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this study is to examine the association between physical and sexual violence exposure and somatic symptoms among female adolescents. We studied a nationally representative sample of 8,531 females, aged 11-21 years, who participated in the 1994-1995 Wave I of the National Longitudinal Study of Adolescent Health (Add Health). Female adolescents were asked how often they had experienced 16 specific somatic symptoms during the past 12 months. Two summary categorical measures were constructed based on tertiles of the distributions for the entire female sample: (a) total number of different types of symptoms experienced, and (b) number of frequent (once a week or more often) different symptoms experienced. Groups were mutually exclusive. We examined associations between adolescents' violence exposure and somatic symptoms using multinomial logistic regression analyses. About 5 % of adolescent females reported both sexual and non-sexual violence, 3 % reported sexual violence only, 36 % reported non-sexual violence only, and 57 % reported no violence. Adolescents who experienced both sexual and non-sexual violence were the most likely to report many different symptoms and to experience very frequent or chronic symptoms. Likelihood of high symptomatology was next highest among adolescents who experienced sexual violence only, followed by females who experienced non-sexual violence only. Findings support an exposure-response association between violence exposure and somatic symptoms, suggesting that symptoms can be markers of victimization. Treating symptoms alone, without addressing the potential violence experienced, may not adequately improve adolescents' somatic complaints and well-being.
    Maternal and Child Health Journal 01/2013; · 2.24 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Women who experience intimate partner violence (IPV) during pregnancy also tend to experience depressive symptoms. Unfortunately, little is known about how victimized women's levels of depressive symptoms change longitudinally before pregnancy, during pregnancy, and after infant delivery. In addition, few studies have used a comparison group of women to determine if levels of depressive symptoms among victimized women differ from depressive symptom levels in women who have not experienced IPV. To help address these knowledge gaps, we examined longitudinal trends in levels of depressive symptoms among a sample of 76 women who did (n = 33) and did not (n = 43) experience physical IPV during pregnancy. Using multilevel analysis, we estimated the relationship of physical IPV victimization and women's depressive symptom levels across six time periods: (a) the year before pregnancy, (b) first and second trimesters, (c) third trimester, (d) the first month postpartum, (e) Months 2 to 6 postpartum, and (f) Months 7 to 12 postpartum. Women who experienced physical IPV victimization during pregnancy had significantly higher levels of depressive symptoms during each time period (p < .05). No significant difference between the two groups was found in the rate of change in levels of depressive symptoms over time. These findings point to the importance of screening for IPV within health care settings and suggest that women physically abused during pregnancy need safety interventions that are coordinated with interventions targeting symptoms of depression.
    Journal of Interpersonal Violence 01/2013; · 1.64 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this study is to examine the association between physical and sexual violence exposure and somatic symptoms among female adolescents. We studied a nationally representative sample of 8,531 females, aged 11–21 years, who participated in the 1994–1995 Wave I of the National Longitudinal Study of Adolescent Health (Add Health). Female adolescents were asked how often they had experienced 16 specific somatic symptoms during the past 12 months. Two summary categorical measures were constructed based on tertiles of the distributions for the entire female sample: (a) total number of different types of symp-toms experienced, and (b) number of frequent (once a week or more often) different symptoms experienced. Groups were mutually exclusive. We examined associations between adolescents' violence exposure and somatic symptoms using multinomial logistic regression analyses. About 5 % of adolescent females reported both sexual and non-sexual violence, 3 % reported sexual violence only, 36 % reported non-sexual violence only, and 57 % reported no violence. Adolescents who experienced both sexual and non-sexual violence were the most likely to report many different symptoms and to experience very frequent or chronic symptoms. Likelihood of high symptomatology was next highest among adolescents who experienced sexual violence only, followed by females who experienced non-sexual violence only. Findings support an exposure– response association between violence exposure and somatic symptoms, suggesting that symptoms can be markers of victimization. Treating symptoms alone, without addressing the potential violence experienced, may not adequately improve adolescents' somatic complaints and well-being.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Presenting continuous outcomes in Summary of Findings tables presents particular challenges to interpretation. When each study uses the same outcome measure, and the units of that measure are intuitively interpretable (e.g., duration of hospitalization, duration of symptoms), presenting differences in means is usually desirable. When the natural units of the outcome measure are not easily interpretable, choosing a threshold to create a binary outcome and presenting relative and absolute effects become a more attractive alternative. When studies use different measures of the same construct, calculating summary measures requires converting to the same units of measurement for each study. The longest standing and most widely used approach is to divide the difference in means in each study by its standard deviation and present pooled results in standard deviation units (standardized mean difference). Disadvantages of this approach include vulnerability to varying degrees of heterogeneity in the underlying populations and difficulties in interpretation. Alternatives include presenting results in the units of the most popular or interpretable measure, converting to dichotomous measures and presenting relative and absolute effects, presenting the ratio of the means of intervention and control groups, and presenting the results in minimally important difference units. We outline the merits and limitations of each alternative and provide guidance for meta-analysts and guideline developers.
    Journal of clinical epidemiology 10/2012; · 5.33 Impact Factor
  • CHANCE 09/2012; 14(1):30-35.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study is to estimate rates of suicide and homicide death among pregnant, postpartum and non-pregnant/non-postpartum women ages 14-44, and to determine comparative rates of violent death for pregnant and/or postpartum women compared to non-pregnant/non-postpartum women. North Carolina surveillance and vital statistics data from 2004 to 2006 were used to examine whether pregnant or postpartum women have higher (or lower) rates of suicide and homicide compared to other reproductive-aged women. The suicide rate for pregnant women was 27% of the rate for non-pregnant/non-postpartum women (rate ratio= 0.27, 95% CI = 0.11-0.66), and the suicide rate for postpartum women was 54% of the rate for non-pregnant/non-postpartum women (rate ratio = 0.54, 95% CI = 0.31-0.95). Homicide rates also were lower for pregnant and postpartum women, with the homicide rate for pregnant women being 73% of the rate for non-pregnant/non-postpartum women (rate ratio = 0.73, 95% CI = 0.39-1.37), and the homicide rate for postpartum women being half the rate for non-pregnant/non-postpartum women (rate ratio = 0.50, 95% CI = 0.26-0.98). Although pregnant and postpartum women are at risk for homicide and suicide death, the highest risk group is non-pregnant/non-postpartum women. Violence prevention efforts should target all women of reproductive age, and pay particular attention to non-pregnant/non-postpartum women, who may have less access to health care services than pregnant and postpartum women.
    Maternal and Child Health Journal 07/2011; 15(5):660-9. · 2.24 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Concerns have been expressed about the validity of self-reported data on sexual assault, as victims might be reluctant to disclose what happened to them. In this study, using an anonymous, web-based survey, a sample of 5,446 undergraduate women were asked about their experiences with physically forced sexual assault using both direct and indirect questioning methods. The prevalence of physically forced sexual assault obtained via indirect questioning was slightly higher than, though not substantially or statistically different from, the estimate obtained via direct questioning. The results suggest that either direct questioning yields reasonably valid estimates of the prevalence of sexual assault or that the item count technique does not produce estimates that are any more valid.
    Violence Against Women 02/2011; 17(2):219-35. · 1.33 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigated agency directors' perspectives about how service goals should be prioritized for domestic violence and sexual assault service subtypes, including crisis, legal advocacy, medical advocacy, counseling, support group, and shelter services. A sample of 97 (94% response rate) North Carolina domestic violence and/or sexual assault agency directors completed a survey asking participants to rank the importance of service goals. Overall, participants considered emotional support provision to be a critical service goal priority across all service types. Social support and self-care service strategies were deemed less important. However, prioritization of other service goals varied depending on the service type. Statistically significant differences on service goal prioritization based on key agency characteristics were also examined, and agency characteristics were found to relate to differences in service goal prioritization.
    Journal of Interpersonal Violence 01/2011; 26(16):3361-82. · 1.64 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We sought to examine relationships between women's sexual orientations and their sexual assault experiences before and during university. Self-reported responses on a web-based survey of 5,439 female undergraduates who participated in the Campus Sexual Assault study were analyzed to compare three groups: bisexuals, lesbians, and heterosexuals. Groups were compared in terms of the prevalence of sexual assault before and during university, and the extent to which sexual assault before university predicted sexual assault during university. The prevalence of sexual assault before and during university was higher among bisexuals and lesbians compared with heterosexuals (25.4% of bisexuals, 22.4% of lesbians, and 10.7% of heterosexuals were sexually assaulted before university; 24.0% of bisexuals, 17.9% of lesbians, and 13.3% of heterosexuals were sexually assaulted during university). Sexual assault before university was highly predictive of sexual assault during university, especially among non-heterosexuals. Compared with heterosexuals not sexually assaulted before university (the referent group), previously assaulted non-heterosexuals (bisexuals/lesbians) had eight times the odds of sexual assault during university (adjusted odds ratio [AOR] = 8.75), whereas previously assaulted heterosexuals had four times the odds of sexual assault during university (AOR, 4.40). However, there was no difference in the odds of sexual assault during university between non-heterosexuals not sexually assaulted before university and heterosexuals not sexually assaulted before university. Bisexual and lesbian women are more likely than heterosexual women to be sexually assaulted before and during university. Sexual assault before university is linked to sexual assault during university for all women, with this association being especially pronounced among non-heterosexuals.
    Women s Health Issues 01/2011; 21(3):199-205. · 1.61 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This article examines literature reviews of research articles and dissertations focused on the effectiveness of college- or university-based sexual violence prevention programs. Literature reviews were eligible for inclusion in this article if they examined empirical published peer-reviewed research articles or dissertation research that reported original data; focused on examining the effectiveness of programs that were developed to reduce sexual violence that occurred in college or university settings; offered recommendations for developing and implementing effective college- or university-based sexual assault prevention programs; and reviewed studies that occurred in the United States. Eight review articles met the inclusion criteria. The results suggest that the effectiveness of college- or university-based sexual violence prevention programs varies depending on the type of audience, facilitator, format, and program content. Recommendations from existing reviews of empirical research concerning these program characteristics should be considered by college or university administrators when designing and implementing their own programs on campus.
    Trauma Violence & Abuse 12/2010; 12(2):67-86. · 3.27 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Earlier studies have shown an inverse association between the presence of nausea and vomiting in pregnancy (NVP) and spontaneous abortion (SAB), but no study to date has examined the effects of symptom duration on the risk of SAB. We examined NVP symptom severity and duration in relation to the occurrence of SAB. Data were collected from 2407 pregnant women in three US cities between 2000 and 2004 through interviews, ultrasound assessments and medical records abstractions. Discrete-time continuation ratio logistic survival models were used to examine the association between NVP and pregnancy loss. Lack of NVP symptoms was associated with increased risk for SAB [adjusted odds ratio (OR) = 3.2, 95% confidence interval (CI): (2.4, 4.3)], compared with having any symptoms. Reduced risks for SAB were found across most maternal age groups for those with NVP for at least half of their pregnancy, but the effects were much stronger in the oldest maternal age group [OR = 0.2, 95% CI: (0.1, 0.8)]. The absence of NVP symptoms is associated with an increased risk of early pregnancy loss. As symptom duration decreases, the likelihood of early loss increases, especially among women in the oldest maternal age group.
    Human Reproduction 11/2010; 25(11):2907-12. · 4.67 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Data on 7,424 soldier spouse abuse offenders were analyzed to determine the prevalence of substance use during abusive incidents, and to examine differences between substance-using and non-substance-using offenders. Results showed that 25% of all offenders used substances during abusive incidents, with males and non-Hispanic Whites being more likely to hav e used substances. Substance-using offenders were more likely to perpetrate physical spouse abuse and more severe spouse abuse. These findings underscore the importance of educating military personnel (including commanders) about links between substance use and domestic violence, and of coordinating preventive and therapeutic substance abuse and violence-related interventions.
    Violence Against Women 11/2010; 16(11):1295-310. · 1.33 Impact Factor
  • Ghazaleh Samandari, Sandra L Martin, Sharon Schiro
    [Show abstract] [Hide abstract]
    ABSTRACT: Eighteen articles that examined the extent of homicide among pregnant and/or postpartum women in the United States are reviewed, documenting the studies' methods and findings. Results from proportional mortality analyses (studies that examined only deaths, rather than deaths within a larger population of living individuals) showed a modicum of support for the contention that homicide may account for a greater proportion of the deaths among pregnant/postpartum women than among other women of reproductive age. However, results from more comprehensive analyses that estimated homicide risks/rates (studies that examined deaths within the context of living populations) did not find any evidence to suggest that pregnant/postpartum women experience a greater risk/rate of homicide compared to other women of reproductive age. This difference in findings is discussed in light of the different methodological approaches.
    Trauma Violence & Abuse 01/2010; 11(1):42-54. · 3.27 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Research concerning suicide and homicide in North Carolina is needed so that medical providers and others who develop and implement preventive and therapeutic interventions related to violence have an empirical base from which to work. North Carolina Violent Death Reporting System data composed of death certificates, medical examiner reports, and law enforcement reports were analyzed to examine the prevalence of suicide and homicide in North Carolina during 2004-2007 and to describe the sociodemographic characteristics of suicide and homicide victims. Suicides and homicides accounted for 2.3% of all North Carolina deaths during 2004-2007. There were 12.0 suicides (95% confidence interval [CI], 11.7-12.4) and 7.2 homicides (95% CI, 6.9-7.4) per 100,000 North Carolina residents. Suicide rates were higher among men and boys, whites, non-Hispanics, and persons aged > or = 35 years. Homicide rates were higher among men and boys, American Indians, blacks, Hispanics, and persons aged < or = 24 years. Firearms were the most common method used to commit suicide and homicide, accounting for 59.5% of suicides and 67.0% of homicides. Every day in North Carolina, approximately 3 persons kill themselves and approximately 2 persons are killed by others. Suicide and homicide inflict a high level of preventable mortality in North Carolina. Learning more about these violent deaths will help to inform the development of effective violence-prevention interventions.
    North Carolina medical journal 01/2010; 71(6):519-25.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Using data from the North Carolina Violent Death Reporting System and other sources, we examined ecologic relationships between county (n = 100) disadvantage and intimate partner homicide (IPH), variability by victim gender and county urbanicity, and potential mediators. County disadvantage was related to female-victim homicide only in metropolitan counties (incidence rate ratio [IRR] 1.25); however, disadvantage was associated with male-victim IPH regardless of county urbanicity (IRR 1.17). None of the potential intervening variables examined (shelter availability, intimate partner violence services' funding) was supported as a mediator. Results suggest disparities across North Carolina counties in IPH according to county disadvantage. Future research should explore other potential mediators (i.e., service accessibility and law enforcement responses), as well as test the robustness of findings using additional years of data.
    Violence and Victims 01/2010; 25(3):363-77. · 1.28 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Symptoms of nausea and vomiting in early pregnancy (NVP) are common among pregnant women, but whether some women are more likely than others to experience these symptoms has not been well established. We examined potential risk factors for NVP symptom severity, timing of onset, and duration. We included 2,407 newly pregnant women who participated in a prospective cohort study on early pregnancy health between 2000 and 2004 in three U.S. cities. Data on NVP and other health information were collected through telephone interviews, early gestation ultrasound, and medical record abstractions. Generalized linear models were used to model possible risk factors for each NVP characteristic. Eighty-nine percent of women had NVP; for 99% of these, symptoms started in the first trimester. None of the characteristics examined were associated with having NVP. Among those with NVP, increasing risk of delayed symptoms onset was associated with advancing maternal age; increased risks were also seen among non-Hispanic Black [Risk ratio (RR) = 4.3, 95% confidence interval (CI): 1.6,11.6] and Hispanic women (RR = 2.3, 95% CI:0.4,11.5). NVP symptoms for multigravidae were more likely to last beyond the first trimester with each additional pregnancy. Most pregnant women experienced NVP. Nearly all of them, regardless of characteristics examined, had symptoms beginning in the first trimester. Maternal age, race/ethnicity, and gravidity were associated with delayed onset and symptoms that persisted into the second trimester.
    Maternal and Child Health Journal 12/2009; 15(1):122-7. · 2.24 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To determine the prevalence of patterns of intimate partner violence (IPV) victimization from adolescence to young adulthood, and document associations with selected sociodemographic and experiential factors. We used prospective data from the National Longitudinal Study of Adolescent Health to group 4134 respondents reporting only opposite-sex romantic or sexual relationships in adolescence and young adulthood into four victimization patterns: no IPV victimization, adolescent-limited IPV victimization, young adult onset IPV victimization, and adolescent-young adult persistent IPV victimization. Forty percent of respondents reported physical or sexual victimization by young adulthood. Eight percent experienced IPV only in adolescence, 25% only in young adulthood, and 7% showed persistent victimization. Female sex, Hispanic and non-Hispanic black race/ethnicity, an atypical family structure (something other than two biologic parents, step-family, single parent), more romantic partners, experiencing childhood abuse, and early sexual debut (before age 16) were each associated with one or more patterns of victimization versus none. Number of romantic partners and early sexual debut were the most consistent predictors of violence, its timing of onset, and whether victimization persisted across developmental periods. These associations did not vary by biological sex. Substantial numbers of young adults have experienced physical or sexual IPV victimization. More research is needed to understand the developmental and experiential mechanisms underlying timing of onset of victimization, whether victimization persists across time and relationships, and whether etiology and temporal patterns vary by type of violence. These additional distinctions would inform the timing, content, and targeting of violence prevention efforts.
    Journal of Adolescent Health 11/2009; 45(5):508-16. · 2.97 Impact Factor
  • Ronna L Chan, Sandra L Martin
    [Show abstract] [Hide abstract]
    ABSTRACT: Population-based data were used to examine the association between reproductive aged women's physical and sexual violence experiences in the previous 12 months and subsequent contraception use. This study used a representative sample of adults (2002 North Carolina Behavioral Risk Factor Surveillance System). Multivariable logistic regression analysis was used to model the associations of interest. Approximately 1 in 20 North Carolina reproductive aged women experienced physical and/or sexual violence in the previous 12 months, with physical violence as the most common. Compared to women who experienced no violence in the previous 12 months, experiences with physical violence by itself increased subsequent contraception use, while experience with sexual violence by itself decreased subsequent contraception use. Women with both experiences in the previous 12 months were less likely to be subsequently using contraception (OR=0.1; 95% CI=0.1-0.8). Findings from this study provide further evidence that different experiences with violence may dictate women's subsequent contraception use.
    Contraception 10/2009; 80(3):276-81. · 3.09 Impact Factor
  • Sandra L Martin
    Violence Against Women 05/2009; 15(4):425-7. · 1.33 Impact Factor

Publication Stats

918 Citations
227.33 Total Impact Points

Institutions

  • 1995–2013
    • University of North Carolina at Chapel Hill
      • Department of Maternal and Child Health
      Chapel Hill, NC, United States
  • 2009
    • RTI International
      Durham, North Carolina, United States
  • 2005
    • Johns Hopkins Bloomberg School of Public Health
      • Department of Epidemiology
      Baltimore, MD, United States
  • 2004
    • Johns Hopkins University
      • School of Nursing
      Baltimore, Maryland, United States
    • Duke University
      Durham, North Carolina, United States
    • University of North Carolina at Charlotte
      Charlotte, North Carolina, United States
  • 2002
    • Columbia University
      • Department of Sociomedical Sciences
      New York City, NY, United States