Income Data for Policy Analysis: A Comparative Assessment of Eight Surveys. Content Summaries


Within each of the 14 domains, from five to 13 aspects of each of the eight surveys are described. These domains and their aspects are as follows:

Table 1. Background and Overview provides brief thumbnail descriptions of survey purpose, design, history, file availability and organizational responsibilities.

Table 2. Survey and Sample Design summarizes sampling frames, units, oversamples and response definitions and rates. Housing units, as distinct from group quarters, have cooking facilities and separate entrances. Response thresholds are the criteria that must be met for an interview to be deemed successful rather than non-response from a household or family that could have been interviewed. Initial response rate is the response rate for one-time surveys or the response rate at the first interview for longitudinal surveys.

Table 3. Universe Definitions, Inclusions and Exclusions specifies precise universes, geographic coverage, definition and inclusion or exclusion of specific types of group quarters, treatment of college students living away at school, and of active military, institutionalized and decedents, plus any exclusions not already specified. Institutions are always group quarters, but many group quarters are non-institutional. Military barracks are non-institutional group quarters but excluded—except for the ACS from 2006 forward—as not civilian. College dormitories are non-institutional group quarters but are treated differently in the various surveys.

Table 4. Timing and Fieldwork describes design and fieldwork time frames and timing, rotation patterns, duration in sample for longitudinal surveys and the monthly survey underlying the CPS (ASEC supplement), who is interviewed, and how. Three surveys—SIPP, CPS and ACS—collect data for a household (all persons dwelling in the housing unit or group quarter) and the others for persons in a family (or narrower) unit. This table also describes the elaborate follow-up process for the mail-out ACS.

Table 5. Longitudinal Inclusion and Follow Rules for the five longitudinal surveys that follow persons over time, summarizes the complex rules on inclusion, exclusion and retention in sample over time, and describes when data is collected for persons no longer in sample, re-contact efforts, and attrition. The monthly survey underlying the CPS ASEC, although it returns to the same addresses repeatedly, is not included since it does not obtain longitudinal information on specific persons–persons moving from the sample address leave the survey.

Table 6. Family Definitions specifies the meaning of the terms “family” and “spouse” for each survey, and differences from the CPS definitions for surveys using these terms differently. This table also provides the definitions of related and unrelated subfamilies for surveys that use those concepts, and summarizes the information available in each survey on relationships, subfamilies, marriage and parents. When descriptions say an item, e.g., parent or legal spouse or sub-family, is “identified”, it means there is a separate variable or marker on the file with that information. Surveys that interview at the family (rather than household) level either exclude unrelated subfamilies (HRS and PSID) or treat them as a separate primary family (MEPS and NHIS). When treated as a separate primary family, a family reference person is identified and the same information is obtained as for the household’s primary family. PSID and HRS (neither of which use a CPS family definition) sometimes use the term household interchangeably with family, and HRS uses the term household for a one- or two-person unit that may be part of a family.

Table 7. Work Activity and Earnings provides short descriptions of employment and labor force information available for the income reference year, level of detail on industry and occupation, and for what persons. This table also describes employment and labor force information available for other reference periods, and whether employment data and earned income data are cross-edited for consistency. CPS definitions of labor force status (used in official statistics) draw a clear distinction between unemployment and not in the labor force. A person must be both available for work and have been actively looking for a job in the past four weeks to be classified as unemployed. In labor force statistics, full time work is 35 hours per week. Class of worker as used in CPS and labor force data is a brief categorization of a person’s employment as either private, armed forces, federal, state or local government, incorporated or unincorporated self-employment, working without pay or not working.

Table 8. Pre-Tax Money Income describes the detail, reference periods, differences from CPS definitions, population covered, recall interval, and person as compared to family level of income data available for each survey, and how it is collected. Descriptions are based on data files, not on questionnaires. The aspect “Screeners” describes whether yes/no or other questions are used to identify persons receiving income from specific sources so non-recipients can be skipped around questions on amounts. The aspect “Brackets” describes data on dollar ranges when respondents don’t know or refuse queries on exact dollar amounts. The entry “brackets” indicates an offer of a number of ranges from which to choose. The entry “unfolding brackets” indicates a less direct method of determining a dollar range, where the respondent is asked if the amount exceeds some (entry) level, then asked whether (depending on the response) it exceeds or is less than a succession of steps until both upper and lower bounds, e.g., a bracket, have been established.

Note that HRS, and RAND materials on the HRS, apply the term “household” to the age-eligible person and spouse or partner, regardless of the other related or unrelated persons with whom they may be living. RAND “household income” refers only to the income of the surveyed individual or couple.

Table 9. Income Allocation and Top-Coding on Public Use Files summarizes some of the changes made in processing raw survey data to fill in blanks, improve quality and/or protect confidentiality, especially top-coding and suppressions, and whether changes in income data to protect confidentiality prevent tabulations on public use files from matching published totals.

Table 10. Poverty Status describes the poverty status (ratio of family income to the poverty threshold used in official statistics for families of that size and composition) that has been and/or can be calculated, and how the universe, family, income and/or timing differ from the official poverty measure contained in the CPS.

Note that poverty status calculations for the PSID have a different measurement structure than in the CPS and can only be replicated in SIPP. In the CPS (and other surveys), poverty thresholds based on family composition as of a fixed date are compared with prior year income of members of the family as of that date. In the PSID, an average annual poverty threshold that reflects changes in family size or composition during the year (is a weighted average of the thresholds appropriate for different part-year compositions) is compared with prior calendar year family income calculated by including part-year amounts for persons there only part of the year.

Table 11. Non-Cash Benefits and Health Insurance summarizes information available, and for which persons, on Food Stamps, other nutrition, housing, energy and welfare to work assistance, and the detail and timing (current coverage, ever-covered prior year, or month-by-month in the prior or current year) of information on public and private health insurance including coverage from or to persons outside the household or family.

Table 12. Person-Level Health and Health Care Utilization describes information on health status, disability, health care services utilization, health conditions and whether conditions associated with disability and/or limitations in activities and/or utilization of health care services are identified, informal care, providers and types of services, and payments, costs, and sources of payment. The event or encounter level information available in MEPS and MCBS constitute a group of very large separate files comparable to (and for MCBS based on) medical claims or bill files.

Table 13. Weights and Control Totals provides an overview of weighting strategy and post-stratification, what weights are available for cross-section and longitudinal analysis, and the relationship of person weights and universes to family or household weights and universes.

Table 14. Ease of Access describes the availability of files with income data, including cost, approval or other barriers or limitations on use, complexity of files and degree of variable construction or assembly needed for calendar year analyses, and availability, accessibility, comprehensiveness and content of survey and file descriptions, questionnaires, data dictionaries, interviewer instructions, technical descriptions of sample design and weights, glossaries and technical assistance.

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