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 inspreadsheet format (.csv) and the full report includingtables and graphics in .pdf format are available on BJS website at http://www.bjs.gov/index.cfm?ty=pbdetail&iid=5280 This reports is one in series. More recent editions may be available. To view a list of all reports in the series go to http://www.bjs.gov/index.cfm?ty=pbse&sid=65 ------------------------------------------------------ Crime Against Persons with Disabilities, 2009–2013 - Statistical Tables Erika Harrell, Ph.D., BJS Statistician The rate of violent victimization against persons with disabilities (36 per 1,000) was more than twice the age- adjusted rate for persons without disabilities (14 per 1,000) in 2013. Persons with disabilities experienced 1.3 million violent victimizations, accounting for 21% of all violent victimizations (figure 1). Nonfatal violent crimes include rape, sexual assault, robbery, aggravated assault, and simple assault. The findings in this report are based on the Bureau of Justice Statistics’ (BJS) National Crime Victimization Survey (NCVS), a household survey that collects data on U.S. residents age 12 or older (excluding those living in institutions). The NCVS adopted survey questions from the U.S. Census Bureau’s American Community Survey (ACS) to identify crime victims with disabilities. The NCVS defines disability as the product of interactions among individuals’ bodies; their physical, emotional, and mental health; and the physical and social environment in which they live, work, or play. Disability exists where this interaction results in limitations of activities and restrictions to full participation at school, at work, at home, or in the community. Disabilities are classified according to six limitations: hearing, vision, cognitive, ambulatory, self- care, and independent living. Data from the ACS were used to estimate age-adjusted victimization rates for persons without disabilities. Unless stated as age-adjusted, findings are unadjusted. For this report, victimization rates were generated by using the ACS population estimates for persons with disabilities. The Methodology further details data sources, computational procedures, and data limitations. The statistical tables in this report detail the level and rates of nonfatal violent victimization against persons with and without disabilities, describe the types of disabilities, and compare victim characteristics. They also include information on the crime incident, such as time of the crime, police notification of the crime, and information on victim services. With the exception of figure 1, all estimates are based on 2-year rolling averages centered on the most recent year. For example, estimates reported for 2013 represent the average estimates for 2012 and 2013. This method improves the reliability and stability of estimate comparisons over time. ******************************************************** *************** List of tables *************** Table 1. Rates of violent victimization, by victim’s disability status and age, 2009–2013 Table 2. Rates of violent victimization against persons with and without disabilities, by type of crime, 2009–2013 Table 3. Rates of violent victimization against persons with and without disabilities, by victim characteristics, 2009–2013 Table 4. Rates of violent victimization against persons with disabilities, by disability type, 2009–2013 Table 5. Rates of serious violent victimization against persons with disabilities, by disability type, 2009–2013 Table 6. Rates of simple assault against persons with disabilities, by disability type, 2009–2013 Table 7. Rates of violent victimization, by victim’s sex and disability type, 2009–2013 Table 8. Percent of violence against persons with disabilities that involved victims with multiple disability types, by type of crime, 2009–2013 Table 9. Rates of violent victimization, by number of disability types and type of crime, 2009–2013 Table 10. Victim–offender relationship, by victim’s disability status, 2009–2013 Table 11. Time violent crime occurred, by victim's disability status, 2009–2013 Table 12. Percent of violent crime reported to police, by victim's disability status, 2009–2013 Table 13. Person who notified police of violent crime, by victim's disability status, 2009–2013 Table 14. Reasons for not reporting violent crime to police, by victim’s disability status, 2009–2013 Table 15. Percent of violent crime victims who received services from nonpolice victim services agencies, by victim's disability status, 2009–2013 ********************************************************* ************************ List of appendix tables ************************ Appendix table 1. Estimates for figure 1: Annual number of violent victimizations, by victim’s disability status, 2008–2013 Appendix table 2. Standard errors for figure 1: Annual number of violent victimizations, by victim’s disability status, 2008–2013 Appendix table 3. Standard errors for table 1: Rates of violent victimization, by victim’s disability status and age, 2009–2013 Appendix table 4. Standard errors for table 2: Rates of violent victimization against persons with and without disabilities, by type of crime, 2009–2013 Appendix table 5. Standard errors for table 3: Rates of violent victimization against persons with and without disabilities, by victim characteristics, 2009–2013 Appendix table 6. Standard errors for table 4: Rates of violent victimization against persons with disabilities, by disability type, 2009–2013 Appendix table 7. Standard errors for table 5: Rates of serious violent victimization against persons with disabilities, by disability type, 2009–2013 Appendix table 8. Standard errors for table 6: Rates of simple assault against persons with disabilities, by disability type, 2009–2013 Appendix table 9. Standard errors for table 7: Rates of violent victimization, by victim’s sex and disability type, 2009–2013 Appendix table 10. Standard errors for table 8: Percent of violence against persons with disabilities that involved victims with multiple disability types, by type of crime, 2009–2013 Appendix table 11. Standard errors for table 9: Rates of violent victimization, by number of disability types and type of crime, 2009–2013 Appendix table 12. Standard errors for table 10: Victim– offender relationship, by victim’s disability status, 2009–2013 Appendix table 13. Standard errors for table 11: Time violent crime occurred, by victim’s disability status, 2009–2013 Appendix table 14. Standard errors for table 12: Percent of violent crime reported to police, by victim's disability status, 2009–2013 Appendix table 15. Standard errors for table 13: Person who notified police of violent crime, by victim's disability status, 2009–2013 Appendix table 16. Standard errors for table 14: Reasons for not reporting violent crime to police, by victim’s disability status, 2009–2013 Appendix table 17. Standard errors for table 15: Percent of violent crime victims who received services from nonpolice victim services agencies, by victim's disability status, 2009–2013 Appendix table 18. U.S. population, according to the U.S. Census Bureau's ACS PUMS data, by disability status and demographic characteristics, 2013 Appendix table 19. Rates of violent victimization against persons without disabilities, by type of crime, 2009–2013 Appendix table 20. Standard errors for appendix table 19: Rates of violent victimization against persons without disabilities, by type of crime, 2009–2013 Appendix table 21. Rates of violent victimization against persons without disabilities, by victim characteristics, 2009–2013 Appendix table 22. Standard errors for appendix table 21: Rates of violent victimization against persons without disabilities, by victim characteristics, 2009–2013 ************************************************************ ************************************* Violent crime by victim’s age and disability status ************************************* * In 2013, for each age group measured except for persons age 65 or older, the rate of violent victimization against persons with disabilities was at least double the rate for those without disabilities (table 1). Among persons age 65 or older, there was no statistically significant difference in the rate of violent victimization by disability status (4 per 1,000). * Except for persons ages 50 to 64 with disabilities, there was no statistically significant difference in the 2012 and 2013 rates of violent victimization against persons with disabilities for each of the age groups measured. Among persons ages 50 to 64 with disabilities, the rate of violent victimization increased from 2012 (28 per 1,000) to 2013 (42 per 1,000). ****************************************** ******************************** The use of age-adjusted rates ******************************** The differences in age distributions between the two populations must be taken into account when making direct comparisons of the violent victimization rate between persons with and without disabilities. The age distribution of persons with disabilities differs considerably from that of persons without disabilities, and violent crime victimization rates vary significantly with age. According to the U.S. Census Bureau’s American Community Survey (ACS), persons with disabilities are generally older than persons without disabilities. For example, about 42% of persons with disabilities were age 65 or older in 2013, compared to 12% of persons without disabilities (appendix table 18). The age adjustment standardizes the rate of violence to show what the rate would be if persons without disabilities had the same age distribution as persons with disabilities. ******************************************** ************************************* Violent crime by type of crime ************************************* * The rate of violent victimization against persons with disabilities (36 per 1,000) was more than twice the age- adjusted rate for persons without disabilities (14 per 1,000) in 2013 (table 2). * In 2013, the rate of serious violent victimization for persons with disabilities (14 per 1,000) was more than three times higher than the age-adjusted rate for persons without disabilities (4 per 1,000). * The rate of simple assault against persons with disabilities (22 per 1,000) was more than twice the age- adjusted rate for persons without disabilities in 2013 (10 per 1,000). * No statistically significant difference was found in the 2009, 2012, and 2013 rates of violent crime against persons with disabilities. The same pattern was found in the age- adjusted rates of violent crime against persons without disabilities. * The rate of aggravated assault against persons with disabilities increased from 4 per 1,000 in 2009 to 7 per 1,000 in 2013. * There was no statistically significant difference found in the 2009 and 2013 rates of rape or sexual assault, robbery, and simple assault against persons with disabilities. * Serious violence (rape or sexual assault, robbery, or aggravated assault) in 2013 accounted for a greater percentage of violence against persons with disabilities (39%) than violence against persons without disabilities (29%) (not shown). * In 2013, 24% of violent crime victims with disabilities believed they were targeted due to their disability, an increase from 2009 (13%) (not shown). ************************************* Violent crime rates by sex, race, and Hispanic origin ************************************* Sex ****** * In 2013, for both males and females, the rate of violent victimization was higher for persons with disabilities than the age-adjusted rate for those without disabilities (table 3). * The unadjusted rate of violent victimization against males with disabilities was 37 per 1,000 in 2013, compared to the age-adjusted rate of 16 per 1,000 for males without disabilities. * For females with disabilities, the rate of violence was 35 per 1,000 in 2013, compared to 12 per 1,000 females without disabilities. * In 2013, no statistically significant difference was found in the rate of violent victimization against males with disabilities (37 per 1,000) and females with disabilities (35 per 1,000). However, among persons without disabilities, males (16 per 1,000) had a higher age-adjusted rate than females (12 per 1,000). * The rate of violence against males with disabilities increased from 26 per 1,000 to 37 per 1,000 from 2009 to 2013. No statistically significant difference was found for females over the same period. * For males and females with disabilities, there was no statistically significant difference in the 2012 and 2013 rates of violent victimization. Race and Hispanic origin **************************** * For each racial group measured except for blacks, persons with disabilities had higher age-adjusted violent victimization rates than the age-adjusted rates of persons without disabilities in 2013. * Among blacks, the apparent difference in the rates of violent victimization by disability status in 2013 was not statistically significant. * Except for whites, there was no statistically significant difference in the 2009 and 2013 rates of violent victimization among persons with disabilities for each racial group examined. * The rate of violent victimization against whites with disabilities increased from 28 per 1,000 in 2009 to 38 per 1,000 in 2013. * In 2013, among persons with disabilities, whites (38 per 1,000) and blacks (31 per 1,000) had higher rates of violent victimization than persons of other races (15 per 1,000). * There was no difference found in the unadjusted and age- adjusted rates of violent victimization against persons of Hispanic origin with and without disabilities in 2013. * Among both Hispanics and non-Hispanics, persons with disabilities had a higher unadjusted rate of violent victimization than the age-adjusted rate for persons without disabilities in 2013. Types of disability ********************* * In 2013, persons with cognitive disabilities (67 per 1,000)had the highest rate of violent victimization among all disability types measured (table 4). This was similar to previous years. * In 2013, persons with hearing disabilities (17 per 1,000) had the lowest rate of violent victimization among the disability types examined. * Persons with hearing (8 per 1,000), vision (12 per 1,000), and self-care (9 per 1,000) disabilities had similar rates of serious violent victimization in 2013 (table 5). * The 2013 rate of simple assault against persons with cognitive disabilities (42 per 1,000) was at least twice that of any other disability type measured (table 6). * Among both males and females, those with cognitive disabilities had the highest rate of violent victimization among the disability types measured in 2013 (table 7). * In 2013, among males, those with ambulatory disabilities (38 per 1,000) had a slightly higher rate of violent victimization than those with self-care disabilities (24 per 1,000). Among females, those with ambulatory and self-care disabilities had similar violent victimization rates (28 per 1,000 each). Violent crime by number of disability types ******************************************** * About 51% of violence against persons with disabilities involved victims with multiple disability types in 2013, similar to the percentage found in 2012 (52%), and up slightly from 2009 (41%) (table 8). * The percentage of serious violence against persons with disabilities involving persons with multiple disabilities has increased slightly from 37% in 2009 to 51% in 2013. * In 2013, there was no statistically significant difference in the rates of violent victimization in persons with a single disability type (35 per 1,000) and persons with multiple disability types (37 per 1,000) (table 9). * Persons with a single disability type had a slightly lower rate of rape and sexual assault (1 per 1,000) than those with multiple disability types (3 per 1,000) in 2013. * The 2013 rate of robbery victimization was slightly higher in persons with a single disability type (7 per 1,000) than in persons with multiple disability types (4 per 1,000). * The 2013 rates of aggravated and simple assault did not differ by the number of disability types. * After slightly declining in 2010 and 2011, the rate of violence against persons with a single disability type increased to a similar level found in 2009 (33 per 1,000 in 2009 compared to 35 per 1,000 in 2013). * The rate of violent victimization against persons with multiple disability types increased from 2009 (24 per 1,000) to 2012 (37 per 1,000) and remained steady through 2013. Victim–offender relationship ******************************** * A lower percentage of violence against persons with disabilities was committed by strangers (31%) than against persons without disabilities (39%) in 2013 (table 10). * The percentage of violence against persons with disabilities committed by intimate partners declined from 2009 (22%) to 2011 (14%) and remained steady through 2013 (15%). * In 2013, 41% of violence against persons with disabilities was committed by persons they knew well or by casual acquaintances, compared to 35% of violence against persons without disabilities. Time of crime *************** * For violent crime victims with and without disabilities, a higher percentage of the violence occurred during daytime (6 a.m.–6 p.m.) than during nighttime (6 p.m.–6 a.m.) (table 11). * The percentage of violence against persons with disabilities that occurred during the daytime did not significantly change during the study period. * In 2013, 58% of violent crime against persons with disabilities occurred during the daytime, compared to 53% of violence against persons without disabilities. Police reporting ******************* * In 2013, 48% of violence against persons with disabilities was reported to police, compared to 44% for persons without disabilities (table 12). * During the study period, the percentage of violent crime against persons with disabilities that was reported to police did not change significantly. * In 2013, there was no statistically significant difference by victim disability status in the percentage of violence reported to police. * In 2013, there was no statistically significant difference between the percentages of violence against persons with single disability types (46%) and persons with multiple disability types (49%) being reported to police. * The percentage of violence against persons with multiple disability types that was reported to the police dropped from 61% in 2009 to 44% in 2012 and remained steady in 2013 (49%). * In every year studied, the majority of violent crime against persons with disabilities that was reported to police was done so by the victim (table 13). This was similar to violent crime victims without disabilities. * The percentage of violent crime against persons with disabilities that was reported by the victim declined from 71% in 2009 to 58% in 2013. * While the percentage of violence against persons with disabilities that was reported by other household members and someone official did not change from 2009 to 2013, the percentage of violence reported by someone else increased from 11% in 2009 to 23% in 2013. * In 2013, the most common reason why violent crimes against persons with disabilities were not reported to police was because they were dealt with in another way (44%) (table 14). * In 2013, for each reason for not reporting crime to police that was measured, the percentages were similar by victim disability status. * The percentage of violent crime victims with disabilities whose crimes were not reported to police because they were not important enough to the victim increased slightly from 13% in 2009 to 21% in 2013. Victim services ***************** * In 2013, violent crime victims with disabilities (12%) were somewhat more likely than those without disabilities (8%) to receive assistance from victim services agencies (table 15). * Except for 2010, the percentage of violent crime against persons with disabilities in which the victim received assistance from victim services agencies was slightly higher than for those without disabilities in each year studied. * During the study period, the percentage of violent crime victims with disabilities who received assistance from victim services agencies did not change significantly (between 11% and 15%). ****************** Methodology ****************** Survey coverage ***************** The National Crime Victimization Survey (NCVS) is an ongoing 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 they 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 victims’ 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. All first interviews are conducted in person with subsequent interviews conducted either in person or by phone. New households rotate into the sample on an ongoing basis to replace outgoing households that have been in the 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 persons who are homeless. In 2007, the NCVS adopted questions from the U.S. Census Bureau’s American Community Survey (ACS) to measure the rate of victimization against people with disabilities. The NCVS does not identify persons in the general population with disabilities. The ACS Subcommittee on Disability Questions developed the disability questions based on questions used in the 2000 Decennial Census and earlier versions of the ACS. The questions identify persons who may require assistance to maintain their independence, be at risk for discrimination, or lack opportunities available to the general population because of limitations related to a prolonged (i.e., 6 months or longer) sensory, physical, mental, or emotional condition. More information about the ACS and the disability questions is available on the U.S. Census Bureau website at http://www.census.gov/acs/www/. Changes to the disability questions in the NCVS and ACS in 2008 **************************************** In 2008, the U.S. Census Bureau changed some of the disability questions on the ACS. The question about sensory disability was separated into two questions about blindness and deafness, and the questions about physical disability asked only about serious difficulty walking or climbing stairs. Also, questions on employment disability and going outside of the home were eliminated in 2008. Census Bureau analysis of 2007 and 2008 ACS disability data revealed significant conceptual and measurement differences between the 2007 and 2008 disability questions. The Census Bureau concluded that data users should not compare the 2007 estimates of the population with disabilities and those of later years. Because the 2007 and 2008 NCVS disability questions mirrored the ACS, estimates of victimization of people with disabilities from the 2007 and 2008 NCVS should not be compared. As a result, the 2007 disability data are not presented in this report. Further explanation about incomparability of the 2007 and 2008 ACS disability data is available at http://www.census.gov/acs/www/Downloads/methodology/content_ test/P4_Disability.pdf. Definitions of disability types ********************************* Disabilities are classified according to six limitations: hearing, vision, cognitive, ambulatory, self-care, and independent living. * Hearing limitation entails deafness or serious difficulty hearing. * Vision limitation is blindness or serious difficulty seeing, even when wearing glasses. * Cognitive limitation includes serious difficulty in concentrating, remembering, or making decisions because of a physical, mental, or emotional condition. * Ambulatory limitation is difficulty walking or climbing stairs. * Self-care limitation is a condition that causes difficulty dressing or bathing. * Independent living limitation is a physical, mental, or emotional condition that impedes doing errands alone, such as visiting a doctor or shopping. Disability questions included in the NCVS from 2008 through 2013 ********************************* Questions 169a through 173 169a. Are you deaf or do you have serious difficulty hearing? 169b. Are you blind or do you have serious difficulty seeing even when wearing glasses? 170a. Because of a physical, mental, or emotional condition, do you have serious difficulty-- * concentrating, remembering, or making decisions? * walking or climbing stairs? * dressing or bathing? 170b. Because of a physical, mental, or emotional condition, do you have difficulty doing errands alone, such as visiting a doctor’s office or shopping? 171. Is “Yes” marked in any of 169a–170b? (That is, has the respondent indicated that he/she has a health condition or disability?) 172. During the incident you just told me about, do you have reason to suspect you were victimized because of your health condition(s), impairment(s), or disability(ies)? 173. What health conditions, impairments, or disabilities do you believe caused you to be targeted for this incident? In the ACS, persons ages 12 to 14 are not asked about having an independent living disability and are therefore not included in the populations with independent living disabilities. Even though crime victims ages 12 to 14 receive this question in the NCVS (question 170b), victims ages 12 to 14 who respond affirmatively are excluded from rates of violent victimization against persons with an independent living disability in order to match the age limitations for having an independent living disability in the ACS (age 15 or older). In this report, rates of violence against persons with an independent living disability are per 1,000 persons age 15 or older, compared to rates per 1,000 persons age 12 or older for other disability types. Also, violent crime victims ages 12 to 14 who report in the NCVS that they have an independent living disability and no other disability are classified as not having a disability to be compatible with age limits on disability definitions in the ACS. Limitations of the estimates ********************************* The NCVS was designed to measure the incidence of criminal victimization against the U.S. civilian household population, excluding persons who live in institutions and the homeless. In this report, institutions refer to adult correctional facilities, juvenile facilities, nursing or skilled nursing facilities, inpatient hospice facilities, residential schools for people with disabilities, and hospitals with patients who have no usual home elsewhere. The measures of crime against persons with disabilities (as measured by the NCVS) cover only people with disabilities who are living among the general population in household settings. Subsequently, there is some coverage error in using just the noninstitutionalized population. For example, according to the ACS, about 96% of the 1.3 million people age 65 or older living in institutions had disabilities in 2013 (not shown). Because persons in these facilities would not be covered in the NCVS, estimates of violence against these persons are not counted. The lack of information from the institutions will result in an undercount of violence against persons with disabilities. Certain aspects of the NCVS design can also contribute to an underestimation of the level or type of violence against persons with disabilities. For example, the survey instruments, modes of interview, and interviewing protocols used in the NCVS may not be suited for interviewing people who have difficulty communicating, especially by telephone. Some people have disabilities that limit their verbal communication and use technology to enhance their ability to communicate, but many people do not have access to such technology. Proxy interviews may also lead to an underestimate of violence against persons with disabilities. The survey requires direct interviews with eligible respondents and allows the use of proxy interviews with a caregiver or other eligible party in a limited set of circumstances. A proxy interview is allowed when a respondent is physically or mentally incapable of responding. The survey restrictions on proxy interviews were instituted because someone else may not know about the victimization experiences of the respondent, and because the person providing the information via proxy may be the perpetrator of the abuse or violence experienced by the respondent. Because proxy respondents may be more likely to omit crime incidents or may not know some details about reported incidents, the number or types of crimes against persons with disabilities may be underestimated. In 2013, information about 2% of violent crime incidents against persons with disabilities was obtained from proxy interviews. In addition, 80% of the reports of violent incidents against persons with disabilities obtained through proxy interviews were for simple assault, compared to about 62% of reports of violent incidents against persons with disabilities obtained through nonproxy interviews (not shown). Disability population in the United States ******************************************** According to the ACS, about 14% of the U.S. population age 12 or older living outside of institutions in 2013 had a disability. Characteristics of the population with and without disabilities are compared in appendix table 18. In 2013, among noninstitutionalized persons with disabilities, 48% were male and 52% were female. Whites accounted for about 77% of the population with disabilities, blacks accounted for 14%, and persons of two or more races accounted for 2%. About 11% were Hispanic. About 42% of the population with disabilities was age 65 or older, compared to about 12% of the population without disabilities. The 2013 ACS population estimates of persons by disability status were generated from Public Use Microdata Sample (PUMS) data. Public Use Microdata Sample data ************************************ To generate populations by disability status for 2008 through 2010, the U.S. Census Bureau generated these estimates for the BJS from the full, confidential ACS dataset. Due to budgetary restrictions, PUMS data from the Census Bureau’s ACS were used to calculate populations by disability status for 2011 through 2013. The ACS PUMS dataset is a sample of population and housing unit records from the ACS. Usually, the PUMS files include only about two-thirds of the cases contained in the larger confidential dataset. The ACS PUMS files include the actual responses collected in ACS questionnaires, although some responses have been edited to protect the confidentiality of respondents. The ACS PUMS file included sample weights for each person and housing unit, which were applied to the individual records to expand the sample to estimate totals and percentages of the full population. For more information on PUMS data from the Census Bureau, see http://www.census.gov/acs/www/data_documentation/public_use_ microdata_sample/. Direct standardization ************************** The method used to generate age-adjusted rates of violent victimization of persons without disabilities presented in this report was direct standardization with the population with disabilities as the standard population ***FOOTNOTE 1: For more information on direct standardization, see Curtin, L.R. & Klein, R.J. (1995). Direct standardization (age- adjusted death rates). Healthy People 2000: Statistical Notes, 6 Revised. Available at http://www.cdc.gov/nchs/data/statnt/statnt06rv.pdf.*** Age- adjusted standardization eliminates the problem of different age distributions between and within groups. In general, persons with disabilities are an older population than persons without disabilities. Because crime rates vary by age, direct standardization produces age-adjusted rates for persons without disabilities that would occur if the population without disabilities had the same age distribution as the population with disabilities. The violent victimization rate, age-adjusted using direct standardization (Rd) is calculated as-- Rd = Σ (wa * ra) Where Rd = age-adjusted rate of violent victimization of the population without disabilities calculated using direct standardization wa = weight calculated from the population with disabilities for age-group a ra = unadjusted rate of violent victimization of persons without disabilities in age-group a d = direct standardization. The weight (wa) for age-group a is calculated as— wa = na / N where wa = weight calculated from the population with disabilities for age-group a na = number of persons in age-group a in the population with disabilities N = total number of persons in the population with disabilities. This method produces rates of violent victimization as if the population of interest had the same age distribution as the population with disabilities. To use this method to calculate the violent victimization rate of persons without disabilities, ra would represent the unadjusted violent victimization rate against persons without disabilities in age-group a. Change in direct standardization calculations *********************************************** In previous BJS reports about crimes against persons with disabilities, several different methods have been used to calculate age-adjusted rates. More specifically, changes in the standard population were made. Over the years, the population without disabilities and the 2000 U.S. standard population generated by the U.S. Census Bureau have both been used as the standard population in calculating age- adjusted rates for persons with and without disabilities. Each time a change was made to the standard population, rates for all years were recalculated using the new standard population. This resulted in previous years having different rates from earlier reports. In this report, BJS changed the calculation of victimization rates by disability status. For each year, unadjusted rates were calculated for persons with disabilities. For persons without disabilities, rates were age adjusted to the population of with disabilities for that year. For example, the 2012–2013 rate of violent victimization against persons with disabilities was unadjusted. The 2012–2013 rate of violent victimization for persons without disabilities was age adjusted using the 2012–2013 population with disabilities as the standard population. Nonresponse and weighting adjustments ***************************************** In 2013, about 90,630 households and 160,040 persons age 12 or older were interviewed for the NCVS. Each household was interviewed twice during the year. The response rate was 84% for households and 88% for eligible persons. Victimizations that occurred outside of the United States were excluded from this report. In 2013, 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 2008 to 2013 NCVS data files weighted to produce annual estimates 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 household and person weights. The household weight is commonly used to calculate estimates of property crimes, such as motor vehicle theft or burglary, which are identified with the household. Person weights provide an estimate of the population represented by each person in the sample. Person weights are most frequently used to compute estimates of crime victimizations of persons in the total population. After proper adjustment, both household and person weights are also used to form the denominator in calculations of crime rates. The victimization weights used in this analysis account for the number of persons present during an incident and for repeat victims of when a series of incidents occurs. The weight counts a series of incidents as the actual number of incidents reported by the victim, up to a maximum of 10 incidents. Series victimizations are victimizations that are similar in type but occur with such frequency that a victim is unable to recall each individual event or to describe each event in detail. Survey procedures allow NCVS interviewers to identify and classify these similar victimizations as series victimizations and collect detailed information on only the most recent incident in the series. In 2013, series incidents accounted for about 1% of all victimizations and 4% of all violent victimizations. The approach to weighting series incidents as the number of incidents up to a maximum of 10 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 for counts, percentages, and unadjusted rates ***************************************** 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 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 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. To generate standard errors around numbers and 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. For estimates, standard errors were based on the ratio of the sums of victimizations and respondents across years. BJS conducted tests to determine whether differences in estimated numbers, percentages, and unadjusted rates 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 primary test procedure was the Student’s t-statistic, which tests the difference between two sample estimates. Differences described as higher, lower, or different passed a test at the 0.05 level of statistical significance (95% confidence level). Differences described as somewhat, slightly, or marginally different, or with some indication of difference, passed a test at the 0.10 level of statistical significance (90% confidence level). Caution is required when comparing estimates not explicitly discussed in this report. 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, during 2012 and 2013, 50.3% of simple assault against persons with disabilities involved victims with multiple disability types (see table 8). Using the GVFs, BJS determined that the estimate has a standard error of 3.9% (see appendix table 10). 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 confidence interval around the 50.3% estimate from 2012 and 2013 is 50.3% + 3.9% x ± 1.96 (or 42.6% to 58.1%). In other words, if different samples using the same procedures were taken from the U.S. population during 2012 and 2013, 95% of the time the percentage of violent crimes against persons with disabilities in which the victim had multiple disability types would fall between 42.6% and 58.1%. In this report, a coefficient of variation (CV), representing the ratio of the standard error to the estimate, was also calculated for all estimates. CVs provide a measure of reliability and a means for comparing 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 coefficient of variation is greater than 50%.) Standard error computations and statistical significance for age-adjusted rates ***************************************** Due to the complexity in generating age-adjusted rates of violent crime, other methods were used to compute standard errors and determine statistical significance ***FOOTNOTE 2 For more information on computing standard errors for age-adjusted rates, see Anderson, R.N., & Rosenberg, H.M. (1998). Age standardization of death rates: Implementation of the year 2000 standard. National Vital Statistics Reports, 47 (3). Available at http://www.cdc.gov/nchs/data/nvsr/nvsr47/nvs47_03.pdf.*** The standard error for age-adjusted rates was calculated as-- Sd = √Σ (wa2 * va) Where Sd = standard error for an age-adjusted weight that was computed using direct standardization wa = weight calculated from the population with disabilities for age-group a va = variance calculated age-group-specific rate using information from the generalized variance function (GVF) parameters that the Census Bureau produced for the NCVS. To calculate statistical significance among two age-adjusted rates, the standard errors for the two rates were calculated using the formula above. A Student’s t-statistic also was calculated, which tests the difference between two sample estimates. Differences described as higher, lower, or different passed a test at the 0.05 level of statistical significance (95% confidence level). Differences described as somewhat, slightly, or marginally different, or with some indication of difference, passed a test at the 0.10 level of statistical significance (90% confidence level). Property crime ****************** Measuring property crime against households with persons with disabilities is difficult using the National Crime Victimization Survey (NCVS) due to the nature of capturing property crimes and the placement of the disability questions on the NCVS incident form (NCVS-2). In the NCVS, only the household respondent is asked about property crimes for the entire household. If the household has experienced a property crime, the household respondent is asked about various characteristics defined in the NCVS-2, including their disability status. The household respondent is not asked about the disability status of anyone else in the household. If the household respondent does not report having a disability, the NCVS cannot be used to determine if anyone else in the household has a disability. As a result, property crime by disability status in not included in this report. ************************************************ ******************************************* Crime Victims with Disabilities Awareness Act (Public Law 105-301), 1998 ******************************************* The Crime Victims with Disabilities Awareness Act mandates that the National Crime Victimization Survey (NCVS) include statistics on crimes against people with disabilities and the characteristics of these victims. The act was designed “to increase public awareness of the plight of victims of crime with developmental disabilities, to collect data to measure the magnitude of the problem, and to develop strategies to address the safety and justice needs of victims of crime with developmental disabilities.” Section 5 of the act directed the Department of Justice to include statistics relating to “the nature of crimes against people with developmental disabilities; and the specific characteristics of the victims of those crimes” in the NCVS. This report is a part of the Bureau of Justice Statistics’ (BJS) series on crime against people with disabilities. More information can be found on the BJS website. ************************************************************ The Bureau of Justice Statistics of the U.S. Department of Justice is the principal federal agency responsible for measuring crime, criminal victimization, criminal offenders, victims of crime, correlates of crime, and the operation of criminal and civil justice systems at the federal, state, tribal, and local levels. BJS collects, analyzes, and disseminates reliable and valid statistics on crime and justice systems in the United States, supports improvements to state and local criminal justice information systems, and participates with national and international organizations to develop and recommend national standards for justice statistics. William J. Sabol is director. These statistical tables were prepared by Erika Harrell, Ph.D. Shannan Catalano provided verification. Lynne McConnell and Jill Thomas edited the report. Tina Dorsey produced the report. May 2015, NCJ 248676 *********************************************** *********************************************** Office of Justice Programs Innovation * Partnerships * Safer Neighborhoods www.ojp.usdoj.gov *********************************************** ************************** 5/20/2015/ JER/ 9:00AM **************************