Response rates measure the proportion of completed surveys to those issued, and help measure the accuracy of the CPI. Failure of a data unit to respond at either the data collection stage or estimation stage represents a loss of statistical information which dilutes the accuracy of the sample. We publish response rates annually to assist the data user in judging the accuracy of CPI data. The tables show response rates for all data included in the CPI-U, U.S. city average, by major group. At the U.S. level, the housing (excluding shelter) category includes items like household fuels and utilities, and furnishings and operations; data for shelter is shown separately. We also publish rates for commodities and services and for shelter in selected areas.
Response rates are calculated for the CPI-U at the data collection and data estimation phases for pricing. The response rate at the data collection phase is the number of responding sample units divided by the number of eligible sample units. A sample unit is eligible if it belongs to the defined target population and if it was selected to provide information for one or more items. The percent of the sample used at estimation is defined as the number of sample units used in estimation divided by the number of eligible sample units. Imputed prices, when used in estimation, are counted in this estimate.
We use rent prices imputed by a non-interview adjustment technique in estimation, therefore, all eligible sample units have prices, collected or imputed, that are used in estimation. The response rates at the data collection phase for shelter are separated into three categories. If rent price information is obtained, the unit is designated data reported. If the assigned unit is located but is unoccupied, the unit is designated vacant. In instances where the unit is eligible but no data are available (for example, no contact is made with the rental unit respondent in the pricing month) the unit is designated other. In total, all eligible sample are used in estimation, and equal the sum of data reported, vacant, and other rental units.
The response rates in the tables are separated into commodities and services, and the shelter portion of housing. Commodities and services are further broken down into outlets and quotes. An "outlet" is a generic term that designates the place where prices are collected. A "quote" is a specific item to be priced in a specific outlet. There may be from 1 to more than 50 quotes priced in each outlet. If any quote in an outlet is eligible, collected, and/or used in estimation then the outlet is counted.
In table R-1, it is important to note the relatively low percentages of quotes reported, collected and used in estimation for apparel. Low rates for these items can be partially attributed to the design of the apparel sample. Because seasonal apparel items commonly are in stores only during certain times of the year, most of the apparel sample is doubled, with each half of the sample designated for pricing during part of the year. Thus, at any particular time of the year, a large number of apparel quotes, although eligible, are designated out of season and are not collected.
Last Modified Date: February 8, 2021