U.S. Department of Justice Office of Justice Programs Bureau of Justice Statistics ----------------------------------------------------- This file is text only without graphics and many of the tables. A Zip archive of the tables in this report in spreadsheet format (.csv) and the full report including tables and graphics in .pdf format are available on BJS website at:http://bjs.gov/index.cfm?ty=pbdetail&iid=4536 -------------------------------------------------------- Intimate Partner Violence, 1993–2010 Shannan Catalano, Ph.D., BJS Statistician November 2012, NCJ 239203 From 1994 to 2010, the overall rate of intimate partner violence in the United States declined by 64%, from 9.8 victimizations per 1,000 persons age 12 or older to 3.6 per 1,000 (figure 1; table 1). The number of intimate partner victimizations also declined, from approximately 2.1 million victimizations in 1994 to around 907,000 in 2010—a decline of about 1.2 million victimizations over the 18-year data collection period. From 1994 to 2000, similar declines were observed for overall violent crime (down 47%) and intimate partner violence (down 48%). However, during the more recent 10-year period from 2001 to 2010, the decline in the overall intimate partner violence rate slowed and stabilized while the overall violent crime rate continued to decline. The data in this report were developed from the Bureau of Justice Statistics’ (BJS) National Crime Victimization Survey (NCVS), which annually collects information on nonfatal victimizations reported and not reported to the police against persons age 12 or older from a nationally representative sample of U.S. households. This special report examines trends in nonfatal intimate partner violence which includes rape, sexual assault, robbery, aggravated assault, and simple assault committed by an offender who was the victim’s current or former spouse, boyfriend, or girlfriend. ************ Highlights ************ * From 1994 to 2010, the overall rate of intimate partner violence in the United States declined by 64%, from 9.8 victimizations per 1,000 persons age 12 or older to 3.6 per 1,000. * Intimate partner violence declined by more than 60% for both males and females from 1994 to 2010. From 1994 to 2010, about 4 in 5 victims of intimate partner violence were female. * Females ages 18 to 24 and 25 to 34 generally experienced the highest rates of intimate partner violence. Compared to every other age group, a smaller percentage of female victims ages 12 to 17 were previously victimized by the same offender. * The rate of intimate partner violence for Hispanic females declined 78%, from 18.8 victimizations per 1,000 in 1994 to 4.1 per 1,000 in 2010. * Females living in households comprised of one female adult with children experienced intimate partner violence at a rate more than 10 times higher than households with married adults with children and 6 times higher than households with one female only. Trend estimates are based on two-year rolling averages centered on the most recent year. For example, estimates reported for 1994 represent the average estimates for 1993 and 1994. For ease of discussion, all two-year estimates are referenced by the most recent year. This method improves the reliability and stability of estimate comparisons over time. This report examines long-term trends in intimate partner violence for three-time periods: 1993 to 2000, 2000 to 2005, and 2005 to 2010. ***************************************** From 1994 to 2010, intimate partner violence declined by more than 60% for both males and females ***************************************** Females and males experienced similar overall declines in intimate partner violence from 1994 to 2010. In 1994, the rate of female intimate partner violence was 16.1 victimizations per 1,000 females age 12 or older (figure 2). By 2010, this rate had decreased by 63%, to 5.9 per 1,000. In comparison, male victims of intimate partner violence experienced 3.0 victimizations per 1,000 males age 12 or older in 1994, and this rate had decreased by 64%, to 1.1 per 1,000 in 2010. From 1994 to 2000, similar percentage declines in intimate partner victimization were observed for females (down 48%) and males (down 46%). After this period, trends differed between the two groups. From 2000 to 2005, the rate of intimate partner violence for females continued to decline (down 31%), while male victimization rates remained stable. In comparison, the rate of intimate partner violence against females remained stable from 2005 to 2010, while males experienced a 39% decline, from 1.7 to 1.1 victimizations per 1,000 males age 12 or older. ***************************************** About 4 in 5 victims of intimate partner violence were female from 1994 to 2010 ***************************************** Most intimate partner violence was perpetrated against females. In 1994, 85% of intimate partner violence victims were female and the remaining 15% were male (not shown in figure). These distributions remained relatively stable over time. Because females comprise the majority of intimate partner violence victims, the remainder of this report focuses on females only. This approach is taken because the relatively smaller number of male victims of intimate partner violence inhibits reliable comparisons over time. ***************************************** Rates of intimate partner violence declined for females of all age groups from 1994 to 2000 ***************************************** Females ages 18 to 24 and 25 to 34 generally experienced higher rates of intimate partner violence than females of other age categories from 1994 to 2010 (figure 3). During the period, the rate of intimate partner violence against females ages 25 to 34 declined by 62%, from 31.9 victimizations per 1,000 females ages 25 to 34 to 12.1 per 1,000. In addition, the rates of intimate partner violence against females ages 18 to 24 declined by 71%, from 33.9 victimizations per 1,000 females ages 18 to 24 in 1994 to 9.7 per 1,000 in 2010. The rate of intimate partner violence for females in all age categories declined from 1994 to 2000, but after 2000 the pattern differed between younger and older females. From 2000 to 2005, rates of intimate partner violence continued to decline for females ages 12 to 17 (down 52%), 18 to 24 (down 40%), and 25 to 34 (down 40%), while rates for females ages 35 to 49 and 50 or older remained stable. From 2005 to 2010, rates of intimate partner violence remained stable for females in most age categories, with two exceptions. Females ages 18 to 24 experienced a 34% rate decline in intimate partner violence, from 14.7 victimizations per 1,000 females ages 18 to 24 to 9.7 per 1,000. Females ages 18 to 24 were the only age group to experience declines across all three periods. In comparison, females ages 35 to 49 were the only age group to experience a statistically significant increase in intimate partner violence from 2005 to 2010. From 2005 to 2010, females ages 35 to 49 experienced a slight increase in rates of intimate partner violence, from 7.1 to 9.6 victimizations per 1,000 females ages 35 to 49. The rate of intimate partner victimization declined with age. Compared to all other age groups, females age 50 or older experienced the lowest rates of intimate partner violence both in 1994 (1.5 victimizations per 1,000) and 2010 (1.3 victimizations per 1,000). ***************************************** Compared to every other age group, a smaller percentage of female victims ages 12 to 17 were previously victimized by the same offender ***************************************** Most female victims of intimate partner violence were previously victimized by the same offender, including 77% of females ages 18 to 24, 76% of females ages 25 to 34, and 81% of females ages 35 to 49 (figure 4). In comparison, a smaller percentage of females ages 12 to 17 (38%) indicated that the same offender had previously committed a crime against them. ***************************************** From 1994 to 2010, Hispanic females experienced slightly larger declines in intimate partner violence compared to white and black females ***************************************** Among females who experienced intimate partner violence in 1994, no rate differences were detected between Hispanics (18.8 victimizations per 1,000 females age 12 or older) and black non-Hispanics (20.3 per 1,000), or Hispanics and white non-Hispanics (15.6 per 1,000) (figure 5). White non- Hispanic, black non-Hispanic, or Hispanic females experienced higher rates of intimate partner violence in 1994 compared to females of other racial categories (6.3 per 1,000) which includes females who were American Indians, Alaska Natives, Asian, Native Hawaiians, other Pacific Islanders and females of two or more races. Over the 18-year data collection period, white non-Hispanic and black non-Hispanic females experienced similar cumulative rate declines in intimate partner violence. By 2010, rates for both white non-Hispanics (6.2 victimizations per 1,000) and black non-Hispanics (7.8 per 1,000) females had declined by about 61%. During the same period, the rate for Hispanic females declined by 78%, from 18.8 to 4.1 per 1,000. White non-Hispanic females (down 44%), black non-Hispanic females (down 58%), and Hispanic females (down 64%) experienced declines in intimate partner victimization from 1994 to 2000. White non-Hispanic females were the only racial category to experience a decline in the rate of intimate partner violence from 2000 to 2005 (down 39%). During this same period, the intimate partner victimization rate for black non-Hispanic and Hispanic females remained unchanged. ***************************************** From 1994 to 2010, intimate partner violence declined for females of all marital statuses ***************************************** The overall rate of intimate partner violence among married females declined by 66%, from 5.9 victimizations per 1,000 females age 12 or older in 1994 to 2.0 per 1,000 in 2010. Rates among divorced or widowed females declined by 67%, from 19.9 victimizations per 1,000 in 1994 to 6.5 per 1,000 during the same period. Females who were either separated or never married experienced similar overall percentage declines from 1994 to 2010. Separated females experienced the highest rate of intimate partner violence during the 18-year period. The rate among separated females declined from 151.4 victimizations per 1,000 females age 12 or older in 1994 to 59.6 per 1,000 in 2010. From 2000 to 2005, the rate of intimate partner victimization remained stable for married females, while rates for females who were never married (down 31%), divorced or widowed (down 31%), or separated (down 30%) declined (figure 6). In 2010, the rate of intimate partner violence for married females (2.0 victimizations per 1,000 females age 12 or older) was about four times less than the rates for never married females (8.0 victimizations per 1,000), about three times less than the rate for divorced or widowed females (6.5 victimizations per 1,000), and about 30 times less than the rate for separated females (59.6 victimizations per 1,000). ***************************************** The rate of intimate partner violence for females living in households comprised of married adults with children declined by 74% from 1994 to 2010 ***************************************** Females living in households comprised of married adults with children experienced a 74% decline in intimate partner violence, from 9.6 victimizations per 1,000 females age 12 or older in 1994 to 2.5 per 1,000 in 2010 (figure 7). The rate of intimate victims for females living in households comprised of one female adult with children declined by 57%, from 73.1 per 1,000 in 1994 to 31.7 per 1,000 in 2010. From 1994 to 2000, similar overall declines occurred among households comprised of one female adult only (down 41%) and those with one female adult with children (down 45%). The rate of female intimate partner violence among households with one female adult remained stable from 2000 to 2005. In comparison, the rate among households with one female adult with children declined by more than a third (down 35%), from 40.0 victimizations per 1,000 females in 2000 to 25.9 victimizations per 1,000 in 2005, then remained stable until 2010. In 2010, the rate of intimate partner violence against females living in households comprised of married adults with children was lower than those of households with one female only. The rate of female intimate partner violence in 2010 among households comprised of one female adult with children (31.7 victimizations per 1,000 females age 12 or older) was more than 10 times higher than the rate for females in households with married adults with children (2.5 per 1,000), and more than 6 times higher than the rate for those in households with one female adult only (4.6 per 1,000). ************ Methodology ************ Survey coverage ---------------- The Bureau of Justice Statistics’ (BJS) National Crime Victimization Survey (NCVS) is an annual data collection conducted by the U.S. Census Bureau. The NCVS is a self- report survey in which interviewed persons are asked about the number and characteristics of victimizations experienced during the prior six months. The NCVS collects information on nonfatal personal crimes (rape or sexual assault, robbery, aggravated and simple assault, and personal larceny) and property crimes (burglary, motor vehicle theft, and other theft) both reported and not reported to police. In addition to providing annual level and change estimates on criminal victimization, the NCVS is the primary source of information on the nature of criminal victimization incidents. Survey respondents provide information about themselves (such as age, sex, race and ethnicity, marital status, education level, and income) and whether they experienced victimization. Information are collected for each victimization incident about the offender (such as age, race and ethnicity, sex, and victim–offender relationship), characteristics of the crime (including time and place of occurrence, use of weapons, nature of injury, and economic consequences), whether the crime was reported to police, reasons why the crime was or was not reported, and experiences with the criminal justice system. The NCVS is administered to persons age 12 or older from a nationally representative sample of households in the United States. The NCVS defines a household as a group of members who all reside at a sampled address. Persons are considered household members when the sampled address is their usual place of residence at the time of the interview and when they have no usual place of residence elsewhere. Once selected, households remain in the sample for three years, and eligible persons in these households are interviewed every six months for a total of seven interviews. New households rotate into the sample on an ongoing basis to replace outgoing households that have been in the sample for the three-year period. The sample includes persons living in group quarters, such as dormitories, rooming houses, and religious group dwellings, and excludes persons living in military barracks and institutional settings, such as correctional or hospital facilities, and the homeless. (For more detail, see the Survey Methodology in Criminal Victimization in the United States, 2008, NCJ 231173, BJS website, May 2011.) In 2010, about 41,000 households and 73,300 individuals age 12 or older were interviewed for the NCVS. Each household was interviewed twice during the year. The response rate was 92.3% of households and 87.5% of eligible individuals. Victimizations that occurred outside of the U.S. were excluded from this report. From 1993 to 2010, 1,657 (0.8%) of the total 197,849 unweighted victimizations occurred outside the U.S. and were excluded from the analyses. Additional selection criteria used in this report include violent criminal victimizations and those perpetrated by intimates. From 1993 to 2010, about 22% (42,449) of the total 197,849 unweighted victimizations were classified as violent crimes. During the same period, about 8% (5,385) of the total 65,690 offenders identified by respondents were described as intimates. ***************************************** Weighting adjustments for estimating household victimization ***************************************** Estimates in this report use data from the 1993 to 2010 NCVS data files. These files are weighted to produce annual estimates of victimization for persons age 12 or older living in U.S. households. Because the NCVS relies on a sample rather than a census of the entire U.S. population, weights are designed to inflate sample point estimates to known population totals and to compensate for survey nonresponse and other aspects of the sample design. The NCVS data files include both person and household weights. Person weights provide an estimate of the population represented by each person in the sample. Household weights provide an estimate of the total U.S. household population. Both household and person weights, after proper adjustment, are also used to form the denominator in calculations of crime rates. Victimization weights used in this analysis account for the number of persons present during an incident and for repeat victims of series incidents. The weight counts series incidents as the actual number of incidents reported by the victim, up to a maximum of 10 incidents. Series victimizations are similar in type but occur with such frequency that a victim is unable to recall the details of each individual event. Survey procedures allow NCVS interviewers to identify and classify these similar victimizations as series victimizations and to collect detailed information on only the most recent incident in the series. In 2010, about 3% of all victimizations were series incidents. Weighting series incidents as the number of incidents up to a maximum of 10 incidents produces more reliable estimates of crime levels, while the cap at 10 minimizes the effect of extreme outliers on the rates. Additional information on the series enumeration is detailed in the report Methods for Counting High-Frequency Repeat Victimizations in the National Crime Victimization Survey, NCJ 237308, BJS website, April 2012. *********************************** Intimate partner violence defined *********************************** As defined in the NCVS, intimate partner violence includes rape, sexual assault, robbery, aggravated assault, and simple assault committed by an offender who is the victim’s current or former spouse, boyfriend, or girlfriend. For some victims, intimates are primarily restricted to boyfriends and girlfriends. Others may be inclined to perceive romantic relationships as friends or acquaintances rather than ascribing the level of intimacy associated with a boyfriend or girlfriend. Thus, the characteristics of intimate violence as defined in this report may differ based on how the respondent perceives the relationship with the offender. ***************************** Standard error computations ***************************** When national estimates are derived from a sample, as is the case with the NCVS, caution must be taken when comparing one estimate to another estimate or when comparing estimates over time. Although one estimate may be larger than another, estimates based on a sample have some degree of sampling error. The sampling error of an estimate depends on several factors, including the amount of variation in the responses, the size of the sample, and the size of the subgroup for which the estimate is computed. When the sampling error around the estimates is taken into consideration, the estimates that appear different may, in fact, not be statistically different. One measure of the sampling error associated with an estimate is the standard error. The standard error can vary from one estimate to the next. In general, for a given metric, an estimate with a smaller standard error provides a more reliable approximation of the true value than an estimate with a larger standard error. Estimates with relatively large standard errors are associated with less precision and reliability and should be interpreted with caution. In order to generate standard errors around estimates from the NCVS, the Census Bureau produces generalized variance function (GVF) parameters for BJS. The GVFs take into account aspects of the NCVS complex sample design and represent the curve fitted to a selection of individual standard errors based on the Jackknife Repeated Replication technique. The GVF parameters were used to generate standard errors for each point estimate (such as counts, percentages, and rates) in the report. In this report, BJS conducted tests to determine whether differences in estimated numbers and percentages were statistically significant once sampling error was taken into account. Using statistical programs developed specifically for the NCVS, all comparisons in the text were tested for significance. The primary test procedure used was Student’s t-statistic, which tests the difference between two sample estimates. To ensure that the observed differences between estimates were larger than might be expected due to sampling variation, the significance level was set at the 95% confidence level. Data users can use the estimates and the standard errors of the estimates provided in this report to generate a confidence interval around the estimate as a measure of the margin of error. The following example illustrates how standard errors can be used to generate confidence intervals: According to the NCVS, in 1994, the overall rate of intimate partner violence was 9.8 victimizations per 1,000 persons age 12 or older (appendix table 1). Using the GVFs, BJS determined that the estimate has a standard error of 0.4 (appendix table 2). A confidence interval around the estimate was generated by multiplying the standard errors by ±1.96 (the t-score of a normal, two-tailed distribution that excludes 2.5% at either end of the distribution). Thus, the confidence interval around the 9.8 estimate from 1994 is equal to 9.8 ± 0.4 X 1.96, (or 9.0 to 10.6). In other words, if different samples using the same procedures were taken from the U.S. population in 1994, 95% of the time the rate of overall intimate partner violence would fall between 9.0 and 10.6 victimizations per 1,000 persons age 12 or older. In this report, BJS also calculated a coefficient of variation (CV) for all estimates, representing the ratio of the standard error to the estimate. CVs provide a measure of reliability and a means to compare the precision of estimates across measures with differing levels or metrics. In cases where the CV was greater than 50%, or the unweighted sample had 10 or fewer cases, the estimate was noted with a “!” symbol (interpret data with caution; estimate is based on 10 or fewer sample cases, or the coefficient of variation exceeds 50%). Many of the variables examined in this report may be related to one another and to other variables not included in the analyses. Complex relationships among variables were not fully explored in this report and warrant more extensive analysis. Causal inferences should not be made based on the results presented. ******************************** Statistical differences defined ******************************** BJS tested the comparisons between the percentages and rates for this report to determine if observed differences were statistically significant. Differences described as higher, lower, or different passed a test at the .05 level of statistical significance (95%-confidence level). Differences described as somewhat, slightly, or marginally different, or some indication of difference, passed a test at the .10 level of statistical significance (90%-confidence level). Caution is required when comparing estimates not explicitly discussed in this bulletin. ***************************************** Methodological changes to the NCVS in 2006 ***************************************** Methodological changes implemented in 2006 may have affected the crime estimates for that year to such an extent that they are not comparable to estimates from other years. Evaluation of 2007 and later data from the NCVS conducted by BJS and the Census Bureau found a high degree of confidence that estimates from 2007 to 2010 are consistent with and comparable to estimates for 2005 and previous years. The reports, Criminal Victimization, 2006, NCJ 219413, December 2007; Criminal Victimization, 2007, NCJ 224390, December 2008; Criminal Victimization, 2008, NCJ 227777, September 2009; Criminal Victimization, 2009, NCJ 231327, October 2010; and Criminal Victimization, 2010, NCJ 235508, September 2011, are available on the BJS website. ******************************************** The Bureau of Justice Statistics is the statistical agency of the U.S. Department of Justice. James P. Lynch is the director. This report was written by Shannan Catalano. Jennifer L. Truman verified the report. Morgan Young and Jill Thomas edited the report, and Barbara Quinn and Morgan Young produced the report, under the supervision of Doris J. James. November 2012, NCJ 239203 ******************************************** ****************************************************** Office of Justice Programs * Innovation * Partnerships * Safer Neighborhoods * http://www.ojp.usdoj.gov ****************************************************** ______________________ 11/19/12/JER/4:38pm ______________________