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://www.bjs.gov/index.cfm?ty=pbdetail&iid=4984 ------------------------------------------------------- ******************* Special Report ******************* Nonfatal Domestic Violence, 2003–2012 Jennifer L. Truman, Ph.D., and Rachel E. Morgan, Ph.D., BJS Statisticians For the 10-year aggregate period 2003–12, domestic violence accounted for 21% of all violent victimizations (figure 1). Domestic violence includes rape, sexual assault, robbery, and aggravated and simple assault committed by intimate partners, immediate family members, or other relatives. Intimate partner violence (15%) accounted for a greater percentage of all violent victimizations, compared to violence committed by immediate family members (4%) or other relatives (2%). Well- known or casual acquaintances accounted for 32% of all violent victimizations, and strangers accounted for 38%. This report uses data from the National Crime Victimization Survey (NCVS) to describe the characteristics and patterns of domestic violence. Domestic violence includes victimizations committed by intimate partners (current or former spouses, boyfriends, or girlfriends), immediate family members (parents, children, or siblings), and other relatives. It details the number, percentage, and demographic characteristics of domestic violence victims, and describes victim and incident characteristics by the victim–offender relationship. Incident characteristics include the type of violence, the offender’s use of a weapon, victim injury and medical treatment, and whether the incident was reported to the police. The report focuses on domestic violence, but includes estimates of violence committed by acquaintances and strangers to provide comparisons. *********************************************** ************ Highlights ************ * This report describes domestic violence—violence committed by intimate partners, immediate family members, or other relatives—by victim and incident characteristics. Data are from the National Crime Victimization Survey (NCVS). In 2003– 12: * Domestic violence accounted for 21% of all violent crime. Intimate partner violence (15%) accounted for a greater percentage of all violent victimizations than violence committed by immediate family members (4%) or other relatives (2%). * Current or former boyfriends or girlfriends committed most domestic violence. * The majority of domestic violence was committed against females (76%) compared to males (24%). * A similar percentage of violence by intimate partners and immediate family members was reported to police (56% each). An estimated 49% of violence by other relatives was reported to police. * Most domestic violence (77%) occurred at or near the victim’s home. * Intimate partner violence resulted in injuries more often than violence perpetrated by immediate family members and other relatives. * A weapon was involved in a larger percentage of violence committed by other relatives (26%) than intimate partners (19%) and immediate family members (19%). *********************************************** The trend estimates are based on 2-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, the report refers to all 2- year estimates by the most recent year. Rolling averages generally improve the reliability and stability of estimate comparisons over time. Other tables in this report focus on the most recent 10-year aggregate period from 2003 through 2012, used throughout the report as 2003–12. Both approaches— using rolling averages and aggregating years—increase the reliability and stability of estimates and facilitate comparisons of detailed victimization characteristics. As with any source of information, there are limitations with the current data that should be recognized. Because the nature of the victim–offender relationship is defined by the victim, the characteristics of intimate partner violence as defined in this report may differ based on how the respondent perceives their relationship with the offender. To some victims, intimate relationships with offenders may be primarily restricted to current or former boyfriends or girlfriends. Others may describe those offenders as friends or acquaintances rather than boyfriends or girlfriends. Also, because the NCVS reflects a respondent’s marital status at the time of the interview, it is not possible to determine whether a person was separated or divorced at the time of the victimization or whether separation or divorce followed the violence. However, most intimate partner violence committed against those with a separated marital status was by a spouse or ex-spouse. *********************************************** ********************************* The National Crime Victimization Survey (NCVS) ********************************* The NCVS collects information on nonfatal crimes reported and not reported to police against persons age 12 or older from a nationally representative sample of U.S. households. It produces national rates and levels of violent and property victimization, information on the characteristics of crimes and victims, and the consequences of victimization. Since the NCVS is based on interviews with victims, it does not measure homicide. This report examines violent crimes, which include rape or sexual assault, robbery, aggravated assault, and simple assault. The Bureau of Justice Statistics (BJS) classifies rape, sexual assault, robbery, and aggravated assault as serious violent crimes. The survey also measures property crime and personal larceny. (For additional estimates not included in this report, see the NCVS Victimization Analysis Tool (NVAT) on the BJS website.) Victimization is the basic unit of analysis used throughout this report. A victimization is a crime as it affects one person or household. For personal crimes, the number of victimizations is equal to the number of victims present during a criminal incident. The number of victimizations may be greater than the number of criminal incidents because more than one person may be victimized during an incident. Each crime against a household is counted as having a single victim, the affected household. The victimization rate is a measure of the occurrence of victimizations among a specified population group. For personal crimes, the victimization rate is based on the number of victimizations per 1,000 residents age 12 or older. For household crimes, the victimization rate is the number of incidents per 1,000 households. The NCVS is administered to persons age 12 or older. Therefore, the survey excludes violence against children under age 12. It includes persons living in group quarters, such as dormitories, rooming houses, and religious group dwellings, but excludes persons living in military barracks and institutional settings, such as correctional or hospital facilities, and the homeless. *********************************************** **************************************** Intimate partner violence accounted for 15% of all violent victimizations **************************************** In 2003–12, intimate partner violence accounted for 14.6% of all violent victimizations (table 1). Current or former boyfriends or girlfriends (7.8%) committed a greater percentage of all violent victimizations than spouses (4.7%) and ex-spouses (2.0%). Violence committed by immediate family members accounted for 4.3% of all violent victimizations, and other relatives accounted for 2.4%. The percentage of total violence perpetrated by other relatives (2.4%) was greater than the percentage by the victim’s parents (1.2%), children (1.5%), or siblings (1.6%). These relationships were similar for serious violence and simple assault. ************************************ Domestic violence declined from 1994 to 2012 ************************************ The rate of domestic violence­ declined 63%, from 13.5 victimizations per 1,000 persons age 12 or older in 1994 to 5.0 per 1,000 in 2012 (appendix table 3). The overall pattern and size of the decline were similar to the decline in the overall violent crime rate. Total violence declined 67% from a rate of 79.8 per 1,000 to 26.1 per 1,000 (not shown). From 1994 to 2012, violence committed by intimate partners declined at a faster rate than violent crime committed by immediate family members and other relatives. Violence committed by intimate partners declined 67%, from 9.8 per 1,000 persons age 12 or older in 1994 to 3.2 per 1,000 in 2012 (figure 2). Violence committed by immediate family members declined 52% during the same period, from 2.7 to 1.3 per 1,000. Violence committed by other relatives decreased 49%, from 1.1 to 0.6 per 1,000. Most of the decline in domestic violence occurred in the first half of the period from 1994 to 2002. Rates of violent crime committed by intimate partners and other relatives continued to decline from 2003 to 2012, while violent crime by immediate family members fluctuated between a rate of 0.9 per 1,000 and 1.3 per 1,000. From 2010 to 2012, violence perpetrated by intimate partners and other relatives remained relatively stable. Serious domestic violence (rape, sexual assault, robbery, and aggravated assault) declined from 1994 to 2012. Serious intimate partner violence declined at a faster rate than serious violence committed by immediate family members and other relatives. Rates of serious intimate partner violence declined by over half, from 3.6 per 1,000 persons age 12 or older in 1994 to 1.0 per 1,000 in 2012 (figure 3). During the same period, the rate of serious violence by immediate family members decreased from 0.7 to 0.3 per 1,000, and serious violence by other relatives decreased from 0.4 to 0.2 per 1,000. Similar to the pattern in overall domestic violence, most of the decline in these rates occurred from 1994 to 2002. Rates of serious intimate partner violence continued to decline from 2003 to 2012. During the same time period, serious violence by immediate family members fluctuated between 0.3 and 0.6 per 1,000, and serious violence perpetrated by other relatives varied between 0.1 and 0.5 per 1,000. Rates of simple assault by intimate partners, immediate family members, and other relatives decreased from 1994 to 2012. The rate of simple assault by intimate partners declined from 6.2 to 2.2 per 1,000 (figure 4). The rate of simple assault by immediate family members decreased from 1.9 to 1.0 per 1,000, while the rate for other relatives declined from 0.7 to 0.4 per 1,000. As in overall domestic violence, the majority of the decline in these rates occurred from 1994 to 2002. Simple assaults by intimate partners remained relatively stable from 2003 to 2012, fluctuating from 2.1 per 1,000 to 3.0 per 1,000. Simple assaults perpetrated by immediate family members varied from a rate of 0.6 per 1,000 to 1.0 per 1,000, and the rate for other relatives fluctuated from 0.3 per 1,000 to 0.5 per 1,000 during the same time period. **************************************** The rate of intimate partner violence was greater than the rate of violence by immediate family members and other relatives **************************************** The rates of violence committed by acquaintances (8.4 victimizations per 1,000 persons age 12 or older) and strangers (10.2 per 1,000) were greater than the rate of domestic violence (5.6 per 1,000) in 2003–12. This was true for both serious violence and simple assault. For total violent crime and serious violent crime, the rate of violence committed by strangers was greater than the rate of violence by acquaintances. In 2003–12, the rate of intimate partner violence (3.9 per 1,000) was greater than the rate of violence by immediate family members (1.1 per 1,000) and other relatives (0.6 per 1,000) (table 2). The rate of intimate partner violence by boyfriends or girlfriends (2.1 per 1,000) was higher than violence perpetrated by spouses (1.3 per 1,000) and ex- spouses (0.5 per 1,000). These patterns were similar for both serious violence and simple assault. The rate of violence committed by siblings (0.4 per 1,000) was greater than the rate by parents (0.3 per 1,000), while the rate of violence perpetrated by parents and children were similar. ****************************************** Domestic violence accounted for a greater percentage of serious violent crime against females than males ****************************************** In 2003–12, a greater percentage of serious violent crime against females was committed by someone the victim knew (65%) than by a stranger (29%) (table 3). In comparison, more serious violent crime against males was committed by a stranger (55%) than by someone the victim knew (34%). A larger percentage of females (37%) were victims of serious domestic violence than males (10%). Both male and female victims were more likely to experience violence by an intimate partner than a family member or other relative. This was also true for simple assault. **************************************** More domestic violence against victims age 18 or older was committed by intimate partners than by immediate family members and other relatives **************************************** In 2003–12, a greater percentage of serious violent crime against victims ages 12 to 17 was committed by someone the victim knew (55%) than by a stranger (37%) (table 4). This pattern held for simple assault. For persons ages 18 to 49, more than 45% of serious violent victimizations were committed by a known offender and more than 43% by a stranger. A larger percentage of simple assault against persons ages 18 to 49 was committed by a known offender (more than 50%) than a stranger (about 40%). Victims ages 12 to 17 and victims age 50 or older experienced more serious violent victimizations and simple assaults involving well-known or casual acquaintances than intimate partners and family members. For victims ages 12 to 17, the percentage of serious violence perpetrated by a family member (7%) was slightly greater than serious violence perpetrated by an intimate partner (5%). A similar pattern was evident for simple assault. Persons age 18 or older experienced more serious domestic violence and simple assault perpetrated by intimate partners than by immediate family members and other relatives. **************************************** The majority of domestic violence was committed against females compared to males **************************************** Among domestic violent victimizations, most were committed against females (76%) compared to males (24%), although the proportions varied by family relationship (figure 5). The majority of intimate partner violence was committed against females (82%), compared to males (18%). However, the proportion of violence against males and females was more evenly distributed for domestic violence perpetrated by immediate family members or other relatives. About 60% of violence by immediate family members and other relatives was committed against females, compared to about 40% of violence committed against males. **************************************** Most domestic violence was committed by the victim’s current or former boyfriend or girlfriend **************************************** In 2003–12, most domestic violence against females was committed by the victim’s current or former boyfriend or girlfriend (39%) or spouse (25%) (figure 6). Similarly, most domestic violence against males was committed by the victim’s current or former boyfriend or girlfriend (30%). Males experienced somewhat similar percentages of domestic violence perpetrated by a spouse (13%), sibling (14%), or other relative (17%). **************************************** Simple assault made up the majority of domestic violence **************************************** In 2003–12, the majority of domestic violence was simple assault (64%), compared to serious violence (36%) (table 5). This pattern held for all victim–offender relationship categories. The majority of violence committed by acquaintances (73%) and strangers (64%) was also simple assault. Violence committed by intimate partners (36%), immediate family members (35%), and other relatives (37%) had similar percentages of serious violence. Current spouses (37%) and current or former boyfriends or girlfriends (38%) committed a higher percentage of serious intimate partner violence than former spouses (22%). **************************************** Intimate partner violence resulted in injuries more often than other types of domestic violence **************************************** In 2003–12, about 45% of domestic violence resulted in injury. Violence perpetrated by intimate partners (48%) resulted in injuries more often than violence perpetrated by immediate family (37%) and other relatives (36%) (table 6). For all domestic violence categories, the majority of physical injuries were bruises or cuts. An estimated 43% of intimate partner violence, 32% of violence by immediate family members, and 31% of violence by other relatives resulted in bruises and cuts. Victims of intimate partner violence (11%) were more likely to suffer serious injuries (i.e., sexual violence injuries, gunshots, knife wounds, internal injuries, unconciousness, and broken bones) than those victimized by immediate family members or other relatives (4% each). Comparatively, more than 21% of violence committed by acquaintances and strangers involved injuries and about 4% involved serious injury. As with domestic violence, when injuries were involved in violence committed by acquaintances or strangers, the majority of these injuries were bruises or cuts. Of the intimate partner violence victims who were injured, 34% received some type of medical care, which was slightly less than the percentage of victims injured by immediate family members (41%) and other relatives (50%). An estimated 49% of intimate partner violence victims and 54% of victims of violence by immediate family members who were injured and sought treatment received care in a hospital or medical office. Of the victims who were injured by other relatives and received care, a greater percentage received care in a hospital or medical office (76%) than at the scene, someone’s home, or another location (24%). In comparison, 37% of victims who were injured by acquaintances received some type of medical care, with the majority receiving that care in a hospital or medical office (61%). A greater percentage of victims who were injured by strangers received medical treatment, compared to victims of intimate partner violence. An estimated 47% of victims who were injured by strangers received treatment. Of those who received treatment, an estimated 61% received care in a hospital or medical office. **************************************** A similar percentage of violence committed by intimate partners and immediate family members involved weapons (19% each) **************************************** In 2003–12, most domestic violence did not involve a weapon (77%) (table 7). A weapon was involved in a larger percentage of violence committed by other relatives (26%) than intimate partners (19%) and immediate family members (19%). However, there were more intimate partner violence victimizations (about 967,700 annually) than victimizations by other relatives (158,900 annually). Annually, about 184,800 intimate partner violent victimizations and about 41,800 victimizations by other relatives involved a weapon. When weapons were involved, firearms made up a smaller percentage than knives and other weapons of domestic violence overall and of intimate partner violence. An equal percentage of domestic violence by other relatives involved firearms and knives (10% each). Although a lower percentage of intimate partner violence (3%) involved a firearm compared to violence by other relatives, the average annual number of intimate partner violence firearm victimizations was greater due to the larger annual average size. As with domestic violence, most violence committed by acquaintances (77%) and strangers (63%) did not involve a weapon. When weapons were involved, a larger percentage of violence committed by acquaintances involved other weapons (7%), compared to firearms (4%) or knives (5%). Strangers used firearms in about 10% of violent crimes, which was similar to the percentage used by other relatives. **************************************** About half of all domestic violence was reported to police **************************************** In 2003–12, about 55% of domestic violence was reported to police (table 8). A similar percentage of intimate partner violence and violence committed by immediate family members was reported to police (56% each). An estimated 49% of violence by other relatives was reported to police. For each category of domestic violence, the percentages reported to police were similar for both serious violence and simple assault. A smaller percentage of violence committed by acquaintances (39%) and strangers (49%) was reported to police, compared to intimate partner violence and violence by immediate family members. **************************************** Victims of intimate partner violence received more assistance from victim service agencies than victims of violence by immediate family members and other relatives **************************************** Victim service agencies are publicly or privately funded organizations that provide victims with support and services to aid their physical and emotional recovery, offer protection from future victimizations, guide victims through the criminal justice system process, and assist them in obtaining restitution. In 2003–12, a greater percentage of victims of intimate partner violence (24%) received assistance from a victim service agency than victims of violence by immediate family members (18%), other relatives (9%), acquaintances (9%), or strangers (4%) (table 9). Victims of serious intimate partner violence (28%) received more assistance than victims of simple assault by an intimate partner (22%). Similarly, victims of serious violence committed by acquaintances (12%) and strangers (5%) received more assistance than victims of simple assault by acquaintances (8%) and strangers (4%). However, the proportions of assistance received by victims of violence committed by immediate family members or other relatives were not statistically different for either serious violence or simple assault. **************************************** Most domestic violence occurred at or near the victim’s home **************************************** In 2003–12, 77% of domestic violence occurred at or near the victim’s home (table 10). Violence by intimate partners (79%) and immediate family members (78%) was more likely to occur at or near the victim’s home than violence committed by other relatives (66%). An estimated 23% of domestic violence occurred in other locations, including a relative’s home, a commercial area, or on public transportation. Unlike domestic violence, most violence committed by acquaintances (61%) and strangers (75%) occurred in other locations, such as commercial places, parking lots or garages, school, or open areas. **************************************** Females had higher rates of domestic violence than males **************************************** In 2003–12, females (6.2 per 1,000) had a higher rate of intimate partner violence than males (1.4 per 1,000) (table 11). The rates of violence committed by immediate family members and other relatives were also higher for females than for males, although males had higher rates of violence by strangers and acquaintances. As with overall violence, rates of domestic violence were highest for persons ages 18 to 24 and lowest for persons age 65 or older. In 2003–12, persons ages 18 to 24 had the highest rates of intimate partner violence (8.7 per 1,000), and persons ages 12 to 17 had the highest rates of violence by immediate family members (2.6 per 1,000). Persons ages 12 to 17 (1.2 per 1,000) and 18 to 24 (1.2 per 1,000) had the highest rates of violence by other relatives. Persons age 65 or older had the lowest rates of violence perpetrated by intimate partners (0.2 per 1,000), immediate family members (0.2 per 1,000), and other relatives (0.1 per 1,000). These patterns held for violence by strangers and acquaintances. Persons ages 12 to 17 had the highest rates of violence committed by acquaintances (26.9 per 1,000), and persons ages 18 to 24 had the highest rate of stranger violence (19.9 per 1,000). Persons age 65 or older had the lowest rates of violence perpetrated by acquaintances (1.3 per 1,000) and strangers (1.6 per 1,000). In 2003–12, non-Hispanic blacks (4.7 per 1,000) and non- Hispanic persons of two or more races (16.5 per 1,000) had the highest rates of intimate partner violence, compared to non-Hispanic whites (3.9 per 1,000), Hispanics (2.8 per 1,000), and non-Hispanic persons of other races (2.3 per 1,000). Persons of two or more races had the highest rate of violence committed by immediate family members (4.4 per 1,000). Whites (1.2 per 1,000) experienced more violence committed by immediate family members than blacks (0.7 per 1,000) and Hispanics (0.6 per 1,000). Blacks (1.2 per 1,000) experienced more violence perpetrated by other relatives than whites (0.6 per 1,000), Hispanics (0.6 per 1,000), and persons of other races (0.2 per 1,000). In 2003–12, blacks and persons of two or more races had the highest rates of violence committed by acquaintances and strangers, compared to whites and persons of other races. The NCVS collects information on a respondent’s marital status at the time of the interview, but does not obtain marital status at the time of the incident or whether a change in marital status occurred after the incident. Rates of intimate partner violence were greater for those persons who were separated (44.7 per 1,000) or divorced (11.4 per 1,000), compared to those who were never married (4.4 per 1,000), married (1.0 per 1,000), or widowed (0.6 per 1,000). Persons who were married or widowed had lower rates of intimate partner violence than those who were never married. Persons who were separated (2.8 per 1,000) also experienced more violence committed by immediate family members than persons in other marital statuses. Persons who were married had lower rates of violence committed by immediate family members (0.6 per 1,000) and other relatives (0.4 per 1,000) than those who were never married, divorced, or separated. Unlike patterns in domestic violence, persons who were never married and separated had higher rates of violence perpetrated by acquaintances and strangers than persons who were married, widowed, or divorced. **************************************** Violence by immediate family members was highest in rural areas **************************************** In 2003–12, the rate of intimate partner violence against urban residents (5.1 per 1,000) was higher than the rate of violence against suburban (3.0 per 1,000) and rural (4.3 per 1,000) residents (table 12). Rural residents had higher rates of violence perpetrated by immediate family members (1.6 per 1,000) than urban (1.2 per 1,000) and suburban (1.0 per 1,000) residents. Rates of intimate partner violence were higher than rates of violence committed by immediate family and other relatives for residents in all areas. The rate of violence committed by acquaintances was higher for victims living in urban (8.8 per 1,000) and rural (9.5 per 1,000) areas than in suburban areas (7.8 per 1,000). Urban areas had the highest rate of stranger violence (14.2 per 1,000). ************** Methodology ************** Survey coverage ***************** The National Crime Victimization Survey (NCVS) is an annual data collection conducted by the U.S. Census Bureau for the Bureau of Justice Statistics (BJS). The NCVS is a self-report survey in which interviewed persons are asked about the number and characteristics of victimizations experienced during the prior 6 months. The NCVS collects information on nonfatal personal crimes (rape or sexual assault, robbery, aggravated and simple assault, and personal larceny) and household 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 (e.g., age, sex, race and Hispanic origin, marital status, education level, and income) and whether they experienced a victimization. The NCVS collects information for each victimization incident about the offender (e.g., age, race and Hispanic origin, 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 the crime was or was not reported, and victim 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 3 years, and eligible persons in these households are interviewed every 6 months either in person or over the phone for a total of seven interviews. Generally, all first interviews are conducted in person. New households rotate into the sample on an ongoing basis to replace outgoing households that have been in sample for the 3-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. Nonresponse and weighting adjustments **************************************** In 2012, 92,390 households and 162,940 persons age 12 or older were interviewed for the NCVS. Each household was interviewed twice during the year. The response rate was 87% for households and 87% for eligible persons. Victimizations that occurred outside of the United States were excluded from this report. In 2012, less than 1% of the unweighted victimizations occurred outside of the United States and were excluded from the analyses. Estimates in this report use data from the 1993 to 2012 NCVS data files, weighted to produce annual estimates of victimization for persons age 12 or older living in U.S. households. Since 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 U.S. household population represented by each household in the sample. After proper adjustment, both household and person weights are also typically 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 high- frequency repeat victimizations (or series victimizations). Series victimizations are similar in type but occur with such frequency that a victim is unable to recall each individual event or describe each event in detail. 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. The weight counts series incidents as the actual number of incidents reported by the victim, up to a maximum of 10 incidents. Including series victimizations in national rates results in large increases in the level of violent victimization; however, trends in violence are generally similar regardless of whether series victimizations are included. In 2012, series incidents accounted for about 1% of all victimizations and 4% of all violent victimizations. 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 web, April 2012. Standard error computations ****************************** When national estimates are derived from a sample, as with the NCVS, it is important to use caution 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 and the size of the sample. When the sampling error around an estimate is taken into account, the estimates that appear different may 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. Generally, an estimate with a small standard error provides a more reliable approximation of the true value than an estimate with a large 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 numbers and estimates from the NCVS, the Census Bureau produced 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 this report. BJS conducted tests to determine whether differences in estimated numbers and percentages in this report 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 Student’s t-statistic was the primary test procedure, which tests the difference between two sample estimates. 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: * In 2003–12, according to the NCVS, 21.3% of all violent victimization was domestic violence (see table 1). Using the GVFs, it was determined that the estimated percentage has a standard error of 0.5 (see 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). Therefore, the 95% confidence interval around the 21.3% estimate from 2012 is 21.3 ± (0.5 X 1.96) or (20.3 to 22.3). In others words, if different samples using the same procedures were taken from the U.S. population in 2003– 12, 95% of the time domestic violence would account for 20.3% to 22.3% of all violent victimizations. 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 based on 10 or fewer sample cases, or the coefficient of variation is greater than 50%). Domestic violence ****************** The NCVS defines domestic violence as rape or sexual assault, robbery, aggravated assault, or simple assault committed by an offender who is the victim’s current or former spouse, boyfriend, girlfriend, parent, child, sibling, or other relative. Intimate partner violence is violence committed by the victim’s current or former spouse, boyfriend, or girlfriend. Because the nature of the victim–offender relationship is defined by the victim, the characteristics of intimate partner violence as defined in this report may differ based on how the respondent perceives their relationship with the offender. To some victims, intimate relationships with offenders may be primarily restricted to current or former boyfriends or girlfriends. Others may describe those offenders as friends or acquaintances rather than boyfriends or girlfriends. This report examines intimate partner violence, violence committed by immediate family members (parents, children, or siblings), and violence committed by all other relatives. 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 for 2007, 2008, 2009, 2010, 2011, and 2012 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; Criminal Victimization, 2010, NCJ 235508, September 2011; Criminal Victimization, 2011, NCJ 239437, October 2012; and Criminal Victimization, 2012, NCJ 243389, October 2013 are available on the BJS website. Although caution is warranted when comparing data from 2006 to other years, the combination of 2-year rolling averages and 10 years of aggregated data in this report diminishes the potential variation between 2006 and later years. In general, findings do not change significantly if the year 2006 is excluded from the analysis. ******************************************************* The Bureau of Justice Statistics, located in the Office of Justice Programs, U.S. Department of Justice, collects, analyzes, and disseminates statistical information on crime, criminal offenders, victims of crime, and the operation of justice systems at all levels of government. William J. Sabol is acting director. This report was written by Jennifer Truman and Rachel Morgan. Erika Harrell verified the report. Vanessa Curto and Jill Thomas edited the report, and Barbara Quinn produced the report. April 2014, NCJ 244697 ******************************************************* ************************************************** Office of Justice Programs Innovation * Partnerships * Safer Neighborhoods www.ojp.usdoj.gov ************************************************** *********************** 3/20/2014/JER/9:30am ***********************