Technical Note The data in this release were collected through a supplement to the September 2015 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-- focuses on obtaining information on employment and unemployment among the nation's civilian noninstitutional population age 16 and over. The purpose of this supplement to the CPS was to obtain information on the incidence of volunteering and the characteristics of volunteers in the United States. 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. 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 may 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 this 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, inability to obtain information for all respondents in the sample, inability or unwillingness of respondents to provide correct information, and errors made in the collection or processing of the data. Additional information on the reliability of data from the CPS and estimating standard errors is available at www.bls.gov/cps/documentation.htm#reliability. The Census Bureau introduces adjustments to the population controls for the CPS as part of its annual update of population estimates. For this reason, data in this release are not strictly comparable with data for earlier years. Additional information is available on the internet at www.bls.gov/cps/documentation.htm#pop. Volunteer questions and concepts In the September supplement, questions on volunteer activities were asked of all households. Efforts were made to have household members answer the volunteer questions for themselves. (Generally, one member of the household answers all the questions in the CPS on behalf of the entire household.) Self-response was considered important for the volunteer supplement because research indicated that self-respondents could more easily answer questions on the characteristics of the volunteer activity. About two-thirds of responses were self-reports. The survey was introduced as follows: "This month, we are interested in volunteer activities, that is, activities for which people are not paid, except perhaps expenses. We only want you to include volunteer activities that you did through or for an organization, even if you only did them once in a while." Following this introduction, respondents were asked the first supplement question: "Since September 1st of last year, have you done any volunteer activities through or for an organization?" If respondents did not answer "yes" to the first question, they were asked the following question: "Sometimes people don't think of activities they do infrequently or activities they do for children's schools or youth organizations as volunteer activities. Since September 1st of last year, have you done any of these types of volunteer activities?" Respondents were considered volunteers if they answered "yes" to either of these questions. This method has been used since the supplement was first administered in 2002. Respondents classified as volunteers were asked further questions about the number and type of organizations for which they volunteered, total hours spent volunteering, how they became involved with the main organization for which they volunteered, the type of activities they performed for the main organization, and what their main activity was. The reference period for the questions on volunteering was about 1 year, from September 1, 2014, through the survey reference week in September 2015. The reference period for other characteristics--such as labor force status, educational attainment, and marital status--refer to the survey reference week in September 2015. It is possible that these characteristics were different at the time volunteer activities were performed. One new question was added to the 2008 survey to determine whether or not respondents had donated money, assets, or property with a combined value of more than $25 to charitable or religious organizations in the past 12 months. Two questions asked in the 2007 supplement were removed in 2008. These questions asked how often respondents who had attended public meetings or who had worked with others in their neighborhood to fix a problem did so. Definitions Volunteers are persons who performed unpaid volunteer activities at any point during the survey reference year. The count of volunteers only includes persons who volunteered through or for an organization; the figures do not include persons who volunteered in a more informal manner. For example, a woman who taught acting to children through a local theater would be considered a volunteer. However, a woman who, on her own, organized softball games for the children in her neighborhood would not be counted as a volunteer for the purpose of this survey. Organizations are associations, societies, or groups of people who share a common interest. Examples include churches, youth groups, and civic organizations. For the purpose of this study, organizations are grouped into eight major categories, including religious, youth, and social or community service organizations. In the 2005 survey, one organization category, immigrant/refugee assistance, was added to the questionnaire as a possible response. Responses that were collected in this category may have been distributed over at least six of the major organization categories in previous years. For this reason, the addition of the new response category created a break in the comparability of organizations between 2005 and prior years. Because few people reported volunteering for immigrant/refugee assistance organizations and because the group was not a definite subset of any of the major organization categories, those persons who did report that they volunteered for immigrant/refugee assistance organizations were placed in the "other" group. The main organization is the organization for which the volunteer worked the most hours during the year. If a respondent volunteered for only one organization, it was considered the main organization, even if exact hours were not obtained. In order to identify the type of main organization, respondents provided information about the organization and, for those who volunteered for more than one organization, annual hours worked for each. Some respondents did not provide the information necessary to determine the main organization. For these respondents, the follow-up questions on activities and how they became involved with the main organization asked them to report on the organization for which they think they spent the most time volunteering. Activities are the specific tasks the volunteer did for an organization. Examples include tutoring, fundraising, and serving food. The activity categories were modified in 2005, thus creating a break in the comparability of activities between 2005 and prior years. In 2006, a new question was added that asked respondents on which of the activities they mentioned they spent the most time. Previously, respondents reported all of the activities they did for their main organization. The new question identified which of them was the main activity for the main organization.