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Handbook of Methods Consumer Expenditures and Income Sample Design

Consumer Expenditures and Income: Sample Design

The Consumer Expenditure Surveys (CE) is a nationwide household survey representing the entire U.S. civilian noninstitutional population. It includes people living in houses, condominiums, apartments, and group quarters such as college dormitories. It excludes military personnel living overseas or on base, nursing home residents, and people in prisons. The civilian noninstitutional population represents more than 98 percent of the total U.S. population.

Selection of households

On behalf of the Bureau of Labor Statistics (BLS), the U.S. Census Bureau collects CE data from a representative sample of households across the United States. The Census Bureau collects data for the Interview Survey and the Diary Survey. BLS first draws the primary sampling units (PSUs) for the Interview Survey and the Diary Surveys. Subsequently, the Census Bureau draws a random sample of households inside those geographic areas.

The selection of households for the survey begins with the definition and selection of PSUs. BLS designs PSUs to be small clusters of counties grouped together into geographic entities called “core-based statistical areas” (CBSAs), which are defined by the Office of Management and Budget (OMB) for use by federal statistical agencies in collecting, tabulating, and publishing federal statistics. BLS uses OMB definitions from 2012 for the CE. There are two types of CBSAs: metropolitan and micropolitan. Metropolitan CBSAs are areas that have an urban “core” of 50,000 or more people, plus the adjacent counties that have a high degree of social and economic integration with the core as measured by commuting ties. Micropolitan CBSAs are similar to metropolitan CBSAs but they have an urban core of 10,000 to 50,000 people. Areas without an urban core or whose urban core is under 10,000 people are called non-CBSA areas. These non-CBSA areas are considered rural PSUs and are defined by BLS rather than by OMB. See a complete list of CBSAs in the United States and a detailed description of how they are defined.

Starting in 2015, the geographic sample used in the survey consists of 91 PSUs that are classified into three categories based on the three PSU types described above and their populations in the 2010 decennial census:

• Self-representing PSUs (known as “S” PSUs) are those selected with certainty. There are 23 “S” PSUs, which are metropolitan CBSAs with a population over 2.5 million people.
• Non-self-representing PSUs (known as “N” PSUs) are those selected randomly. There are 52 “N” PSUs, which are metropolitan and micropolitan CBSAs with a population under 2.5 million people.
• Rural PSUs (known as “R” PSUs). There are 16 “R” PSUs, which are non-CBSA areas.

The 23 “S” PSUs are the largest CBSAs in the country, and they were selected with certainty for the CE sample. The 52 “N” and 16 “R” PSUs are smaller CBSAs and non-CBSA areas that were randomly selected from the rest of the country, with their probabilities of selection being proportional to their populations.  BLS uses all 91 of these PSUs for the CE sample. The Consumer Price Index (CPI) also uses these PSUs in its sample, except it uses only the 23 “S” and 52 “N” PSUs in its sample. The CPI does not use the 16 “R” PSUs because it measures inflation only in urban areas of the country.

Within these 91 PSUs, the list of addresses from which the sample is drawn comes from two sources called “sampling frames.” The primary sampling frame for both the Diary Survey and the Interview Survey is the Census Bureau’s master address file (MAF). That file has all residential addresses identified in the 2010 census and is updated twice per year with the U.S. Postal Service’s delivery sequence file. Over 99 percent of the addresses used in the survey come from the MAF. It is supplemented by a small group quarters frame, which is a list of housing units that are owned or managed by organizations for residents who live in group arrangements such as college dormitories and retirement communities. Less than 1 percent of the addresses used in the CE come from the group quarters frame.

The Interview Survey is a rotating panel survey in which approximately 13,000 addresses are contacted each calendar quarter of the year for the survey. One-fourth of the addresses that are contacted each quarter are new to the survey. Usable interviews are obtained from approximately 5,000 households at those addresses each quarter of the year. After a housing unit has been in the sample for four consecutive quarters, it is dropped from the survey, and a new address is selected to replace it.

The Census Bureau selects a sample of approximately 18,000 addresses per year from the MAF and group quarters frames to participate in the Diary Survey. Usable diaries (two 1-week diaries per household) are obtained from approximately 6,700 households at those addresses. Diaries are not obtained from the other addresses because of refusals, vacancies, ineligibility, or the nonexistence of a housing unit at the selected address. The placement of diaries is spread equally over all 52 weeks of the year. BLS increased the sample sizes in 2020 to obtain sufficient outlet information for the CPI sample design, which previously used a different method of obtaining the information. Prior to 2020, the CE’s sample sizes were 12,000 addresses per calendar quarter in the Interview Survey, and 12,000 addresses per year in the Diary Survey.

Cooperation levels

Response data for the 2019 CE are shown in table 1. For the Interview Survey, each unique CU provides up to four usable interviews per year. For the Diary Survey, each unique CU provides up to two usable diaries (weeks 1 and 2). Most Diary Survey respondents participate in both weeks.

There are three general categories of nonresponse:

• Type A nonresponses are refusals, temporary absences, and noncontacts.
• Type B nonresponses are vacant housing units, housing units with temporary residents, and housing units under construction.
• Type C nonresponses are nonresidential addresses, such as destroyed or abandoned housing units, and housing units converted to nonresidential use.

Response rates are defined as the percentage of eligible housing units (that is, the designated sample less type B and type C nonresponses) from which usable interviews are collected by the Census Bureau. In the 2019 Interview Survey, there were 40,389 eligible housing units from which 21,701 usable interviews were collected, resulting in a response rate of 53.7 percent. In the 2019 Diary Survey, there were 20,244 eligible housing units from which 10,682 usable interviews were collected, resulting in a response rate of 52.8 percent. (See table 1.)