Technical Note The data in this release were collected through the Current Population Survey (CPS). The CPS--a monthly survey of about 60,000 eligible households conducted by the U.S. Census Bureau for the Bureau of Labor Statistics--obtains information on employment and unemployment among the nation's civilian noninstitutional population age 16 and over. Most of the data in this release are annual averages, compiled from the results of the monthly survey. In August, a supplement to the CPS collected additional information about veterans on topics such as service-connected disability, veterans' Reserve or National Guard status, and veterans who served in Iraq and/or Afghanistan. The supplement was co-sponsored by the U.S. Department of Veterans Affairs and by the U.S. Department of Labor's Veterans' Employment and Training Service. Questions were asked of persons 17 years of age and older regarding their prior service in the U.S. Armed Forces. Data are tabulated for persons 18 years of age and older. Information in this release will be made available to sensory impaired individuals upon request. Voice phone: (202) 691-5200; Federal Relay Service: (800) 877-8339. Definitions The definitions underlying the data in this release are as follows: Veterans are men and women who previously served on active duty in the U.S. Armed Forces and who were civilians at the time they were surveyed. Members of the Reserve and National Guard are counted as veterans if they had ever been called to active duty. Persons who are on active duty at the time of the survey are outside the scope of the survey and thus not in the estimates shown here, as are persons who reside in institutions, such as nursing homes and prisons. Nonveterans are men and women who never served on active duty in the U.S. Armed Forces. World War II, Korean War, Vietnam-era, and Gulf War-era veterans are men and women who served in the U.S. Armed Forces during these periods of service, regardless of where in the world they served. Veterans who served in more than one wartime period are classified in the most recent one. Veterans of other service periods are men and women who served in the U.S. Armed Forces at any time other than World War II, the Korean War, the Vietnam era, or the Gulf War era. Although U.S. Armed Forces were engaged in several armed conflicts during other service periods, these conflicts were more limited in scope and included a smaller proportion of the Armed Forces than the selected wartime periods. Veterans who served during one of the selected wartime periods and during another period are classified in the wartime period. Veteran status is obtained from responses to the question, "Did you ever serve on active duty in the U.S. Armed Forces?" Period of service identifies when a veteran served in the Armed Forces, but not the location of their service. It is obtained from answers to the question asked of veterans, "When did you serve on active duty in the U.S. Armed Forces?" The following service periods are identified: Gulf War era II -- September 2001-present Gulf War era I -- August 1990-August 2001 Vietnam era -- August 1964-April 1975 Korean War -- July 1950-January 1955 World War II -- December 1941-December 1946 Other service periods -- All other time periods Veterans could have served anywhere in the world during these periods of service. Veterans are counted only in one period of service, their most recent wartime period. Veterans who served in more than one wartime period are classified in the most recent one. Veterans who served in both a wartime period and any other service period are classified in the wartime period. The period-of-service definitions are modified occasionally to reflect changes in law, regulations, and program needs of the survey sponsors. Veterans who served in Iraq, Afghanistan, or both are individuals who served in Iraq at any time since March 2003, in Afghanistan at any time since October 2001, or in both locations. Service in Iraq or Afghanistan is determined by answers to two questions: "Did you serve in Iraq, off the coast of Iraq, or did you fly missions over Iraq at any time since March 2003?" and "Did you serve in Afghanistan, or did you fly missions over Afghanistan, at any time since October 2001?" Presence of service-connected disability is determined by answers to the question, "Has the Department of Veterans Affairs (VA) or Department of Defense (DoD) determined that you have a service-connected disability, that is, a health condition or impairment caused or made worse by any of your military service?" Service-connected disability rating is based on answers to the question, "What is your current service-connected disability rating?" Answers can range from 0 to 100 percent, in increments of 10 percentage points. Ratings are determined by the VA or DoD from a rating schedule published in the Code of Federal Regulations, Title 38, "Pensions, Bonuses, and Veterans' Relief," Part 4--"Schedule for Rating Disabilities." The rating schedule is "primarily a guide in the evaluation of disability resulting from all types of diseases and injuries encountered as a result of or incident to military service. The percentage ratings represent as far as can practicably be determined the average impairment in earning capacity resulting from such diseases and injuries and their residual conditions in civil occupations." Part 4 contains a listing of hundreds of possible disorders and assigns ratings of 0 through 100 percent, with instructions for rating multiple disorders. Reserve and National Guard membership refers only to Gulf War-era veterans who are current or past members of the Reserve or National Guard. Members of the Reserve and National Guard are counted as veterans if they had ever been called to active duty. These data do not refer to all persons who may have ever served in the Reserve or National Guard. Reserve or National Guard status is obtained from answers to two questions. Gulf War-era veterans were asked: "Was any of your active service the result of a call-up from the Reserve or National Guard?" If the answer was no, they were asked, "Have you ever been a member of the Reserve or National Guard?" A 'yes' response to either question classified persons as "Current or past member of the Reserve or National Guard." A 'no' response to the latter question classified persons as "Never a member of the Reserve or National Guard." Reliability of the estimates Statistics based on the CPS are subject to both sampling and nonsampling error. When a sample, rather than the entire population, is surveyed, there is a chance that the sample estimates will differ from the true population values they represent. The component of this difference that occurs because samples differ by chance is known as sampling error, and its variability is measured by the standard error of the estimate. There is about a 90-percent chance, or level of confidence, that an estimate based on a sample will differ by no more than 1.6 standard errors from the true population value because of sampling error. BLS analyses are generally conducted at the 90-percent level of confidence. The CPS data also are affected by nonsampling error. Nonsampling error can occur for many reasons, including the failure to sample a segment of the population, the inability to obtain information for all respondents in the sample, the inability or unwillingness of respondents to provide correct information, and errors made in the collection or processing of the data. Information about the reliability of national data from the CPS and estimating standard errors is available at www.bls.gov/cps/documentation.htm#reliability. For a discussion of the reliability of state estimates from the CPS, such as those in tables 6A and 6B of this release, see https://www.bls.gov/opub/geographic-profile/home.htm. Comparability of estimates Effective with data for November 2017, estimates for veterans incorporate population controls derived from an updated Department of Veterans Affairs' population model. In accordance with usual practice, BLS did not revise estimates for previous years. Information about the updated veteran population model is available from the Department of Veterans Affairs at https://www.va.gov/vetdata/docs/Demographics/New_Vetpop_Model/Vetpop16_Overview.pdf.