Updating the rent sample for the CPI Housing Survey
The CPI is undertaking a three-stage effort to improve the Housing Survey. The first and second stages use the 2000 Census. The first stage is a 4-year sample augmentation. Its goal is to add 16,000 units, mainly in neighborhoods with seriously depleted renter samples, and increase the size of the sample to its target. The CPI began using data from this augmentation in the OER and Rent indexes for July 2010.
The second stage is a sample replacement to replace the rental units introduced in 1999. The November 2012 CPI was the first that used a new sample from this stage. The May 2016 CPI will be the first in which the Housing Survey sample will have been drawn entirely from the 2000 Census.
The final stage will be a regular replacement commencing in 2016 and ending in 2022. It will replace the 2000-Census-based sample with one based on the American Community Survey using 2010 Decennial Census geography. This stage will continue into the future and—for the first time—the CPI Housing Survey will have a process that keeps its sample continuously updated.
In the 1998 CPI revision, BLS statisticians created special maps that indicated the selected segments and blocks of the pricing areas. Using these maps, CPI field staff traveled to selected segments and “listed” them, meaning that the field staff agents recorded the addresses of all housing units using Computer-Assisted Data Collection (CADC) software on their tablet computers. Then their tablet computers used a sampling algorithm to select a subset of these addresses. The field staff agents then visited each of these addresses and found a respondent to interview. They determined whether each address was eligible for the Housing Survey and, if so, initiated those addresses into the Housing Survey. In many segments, a majority of the addresses were screened out because they were nonresidential, were owner-occupied, or failed some other requirement.
Because of lessons learned in the 1999 sample’s selection and initiation, the CPI is using two important new survey methods in the augmentation and replacement. The 2010 sample augmentation used purchased address lists and a mail prescreening survey to locate housing units in the segments. These steps greatly increased the chances that an address contacted by a BLS agent would be a renter-occupied housing unit eligible for the Housing Survey. The lists indicate the probability that an address is owner-occupied and the addresses provide a means of determining whether an address is a commercial establishment. This information was used to determine sampling rates for the mail prescreening survey and to determine if selected addresses are commercial or residential and, if they are residential, their tenure (owner- or renter-occupied). Only those addresses the survey identified as renter-occupied and those with no response are sent out for BLS field agents to screen. Preliminary results were successful, so purchased address lists and prescreening will be used in all future sample replacements.