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- 4 - Technical Note Survey methodology The data in this release are from the American Time Use Survey (ATUS). The ATUS is a continuous survey, conducted by the U.S. Census Bureau, that collects information about how Americans spend their time. In 2003-06, more than 60,000 individuals were interviewed. Data from approximately 17,000 interviews were used in this release, which shows estimates for a specific reference population--married parents age 15 or over who reside in the same household as their spouses and at least 1 biological, adopted, or step child under 18. The ATUS survey sample is chosen from households that completed their eighth (final) interview for the Current Population Survey (CPS), the nationís monthly household labor force survey. The ATUS sample is selected to ensure the estimates will be nationally representative of the civilian noninstitutionalized population age 15 and over. All ATUS interviews are conducted using Computer Assisted Telephone Interviewing. Procedures are in place to collect information from the small number of households that did not provide a telephone number during the CPS interview. ATUS respondents are preassigned a day of the week about which to report. Preassignment is designed to reduce variability in response rates across the week and to allow oversampling of weekend days, so that accurate weekend day measures can be developed. Interviews occur on the day following the assigned day. For example, a person assigned to report about a Monday would be contacted on the following Tuesday. Ten percent of respondents are assigned to report about each of the five weekdays. Twenty-five percent are assigned to report about each weekend day. House- holds are called for up to 8 consecutive weeks (for example, 8 Tuesdays) in order to secure an interview. About the questionnaire In the core part of the ATUS interview--the time diary--survey respond- ents sequentially report activities they did between 4 a.m. on the day before the interview ("yesterday") until 4 a.m. on the day of the interview. For each activity, respondents are asked how long the activity lasted. If respondents report doing more than one activity at a time, they are asked to identify which one was the "main" activity. If none can be identified, then the interviewer records the first activity mentioned. After completing the time diary, interviewers ask respondents additional questions to clearly identify work activities. In addition, the ATUS includes an update of the household composition information from the last CPS interview (2 to 5 months prior to the ATUS interview) and the employment status information of the survey respondent and his or her spouse. After completing the interview, primary activity descriptions are assigned a single 6-digit code using the ATUS Coding Lexicon. The 3-tier coding system consists of 17 major activity categories, each with multiple second- and third- tier subcategories. These coding lexicon categories are then combined into composite categories for publication, such as in this news release. Descrip- tions of categories shown in this release can be found in the Major activity category definitions section of this Technical Note. The ATUS Coding Lexicon can be accessed at http://www.bls.gov/tus/lexicons.htm. - 5 - Concepts and definitions Average day. The average day measure reflects an average distribution across all persons in the reference population and all days of the week. Average hours per day, population. The average number of hours spent in a 24-hour day doing a specified activity. This is computed using all responses from a given population, including the responses of persons who did not do a particular activity on the day about which they were interviewed. These esti- mates reflect how many population members engaged in an activity and the amount of time they spent doing it. Employment status -- Employed. All persons who, at any time during the 7 days prior to the interview: 1) Did any work at all as paid employees; worked in their own business, profession, or on their own farm; or usually worked 15 hours or more as unpaid workers in a family-operated enterprise; or 2) Were not working but had jobs or businesses from which they were temporarily absent due to illness, bad weather, vacation, childcare problems, labor-management disputes, maternity or paternity leave, job training, or other family or personal reasons, whether or not they were paid for the time off or were seeking other jobs. -- Employed full time. Full-time workers are those who usually worked 35 hours or more per week at all jobs combined. -- Employed part time. Part-time workers are those who usually worked fewer than 35 hours per week at all jobs combined. -- Not employed. Persons are not employed if they do not meet the condi- tions for employment. The not employed include those classified as unemployed as well as those classified as not in the labor force (using CPS definitions). The numbers of employed and not employed persons in this release do not corres- pond to published totals from the CPS for several reasons. First, the reference population for the ATUS is age 15 years and over, whereas it is age 16 years and over for the CPS. Second, ATUS data are collected continuously, the employment reference period being the 7 days prior to the interview. By contrast, CPS data are usually collected during the week including the 19th of the month and refer to employment during the week containing the 12th of the month. Finally, the CPS accepts answers from household members about other household members whereas such proxy responses are not allowed in the ATUS. While the information on employment from the ATUS is useful for assessing work in the context of other daily activi- ties, the employment data are not intended for analysis of current employment trends. Compared with the CPS and other estimates of employment, the ATUS esti- mates are based on a much smaller sample and are only available with a substantial lag since ATUS publication occurs during the year following data collection. - 6 - Married fathers. Married men age 15 or over who reside in the same household as their spouses and at least one biological, adopted, or step child under age 18. Married mothers. Married women age 15 or over who reside in the same household as their spouses and at least one biological, adopted, or step child under age 18. Primary activity. A primary activity is the main activity a respondent was doing at a specified time. The estimates in this release reflect time spent in primary activities. Major activity category definitions The following definitions describe the main activity categories shown in this report: Personal care activities. Personal care activities include sleeping, bathing, dressing, health-related self-care, and personal or private activities. Household activities. Household activities are those done by respondents to maintain their households. These include housework; cooking; yard care; pet care; vehicle maintenance and repair; home maintenance, repair, decoration, and renova- tion; and household management and organizational activities. Purchasing goods and services. This category includes the purchase of consumer goods as well as the purchase or use of professional and personal care services, household services, and government services. Caring for and helping household members. Time spent doing activities to care for or help any child or adult in the respondentís household is classified here. Household members under age 18 are classified as children. Working and work-related activities. This category includes time spent working, doing activities as part of oneís job, engaging in income-generating activities (not as part of oneís job), and job search activities. "Working" includes hours spent doing the specific tasks required of oneís main or other job. "Work-related activities" include activities that are not obviously work but are identified by the respondent as being done as part of oneís job, such as having a business lunch or playing golf with clients. Leisure and sports. The leisure and sports category includes sports, exercise, and recreation; socializing and communicating; watching television; reading; re- laxing or thinking; playing computer, board, or card games; using a computer or the Internet for personal interest; playing or listening to music; and other activities, such as attending arts, cultural, and entertainment events. Travel. The category includes time spent traveling from one destination to another. Other activities, not elsewhere classified. This residual category includes: caring for and helping nonhousehold members; educational activities; eating and drinking; organizational, civic, and religious activities; telephone calls; mis- cellaneous activities not related to a specific category; ambiguous activities that could not be coded; and missing activities. Missing activities result when respondents did not remember what they did for a period of time, or when they considered an activity too private or personal to report. - 7 - Processing and estimation After ATUS data are collected, they go through an editing and imputation pro- cedure. Responses to CPS questions that are re-asked in the ATUS go through the regular CPS edit and imputation procedures. ATUS records are weighted to reduce bias in estimates due to differences in sam- pling and response rates across subpopulations and days of the week. Data in this release are weighted to ensure the following: -- Weekdays represent about 5/7 of the weighted data, and weekend days each represent about 1/7 for the population as a whole. The actual proportions depend on the number of weekdays and weekend days in a given quarter. -- The sum of the weights is equal to the number of person-days in the quarter (or the number of days in the quarter times the population) for the popula- tion as a whole and for selected subpopulations. Reliability of the estimates Statistics based on the ATUS 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 repre- sent. The exact difference, or sampling error, varies depending on the particular sample selected, and this variability is measured by the standard error of the es- timate. There is about a 90-percent chance, or level of confidence, that an esti- mate 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 ATUS data also are affected by nonsampling error. Nonsampling error can occur for many reasons, including the failure to sample a segment of the popula- tion, 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. Errors also could occur if nonresponse is correlated with time use.