Nonresponse is a growing concern for the CPS as well as many other surveys.  Nonresponse rates are constantly monitored, both for basic CPS and the monthly supplements. Methods for reducing nonresponse are investigated and implemented on an ongoing basis. This graph provides the nonresponse rates for basic CPS over the last two years.

Total nonresponse is defined as the number of noninterviews among all eligible households. Nonresponse historically has been highest in March, coinciding with the administration of the Annual Social and Economic Supplement (ASEC). The rates for the two largest categories of nonresponse, refusals and noncontacts ("temporarily absent" and "no one home"), also are given. Recent research has shown that the characteristics of refusals and noncontacts may be quite different, with noncontacts more likely to be employed than refusals. The difference between total nonresponse and the sum of refusals and noncontacts gives an estimate of nonresponse for other reasons, including illness and language problems. Prior to publication, a geographic adjustment for nonresponse is made at the household level. 

In the CPS, households are interviewed for four consecutive months, drop out of the sample for the next 8 months, and then are interviewed again for the same 4 calendar months a year later, before retiring permanently from the sample. This practice avoids placing too heavy a burden on the households selected for the sample, but improves measures of change. Seventy-five percent of the sample remains the same from month to month, and 50 percent from year to year. The overlap of this 4-8-4 rotation scheme helps to improve CPS estimates over time, since the sample's continuity results in a positive correlation between estimates from different months.

Despite this continuity, individual rotation groups are subject to different survey conditions. An empirical illustration of the effects of time in sample can be seen in the graph below. The greater proportion of nonresponse in month-in-samples (MIS) 1 and 5 are likely due to actual differences in response probabilities for these groups. Such differences could arise for a variety of reasons, including mode of interview. With MIS 2-4 and 6-8 households, data collection is primarily by telephone through computer-assisted interviewing; for MIS 1 and 5 household data are typically collected by Census field representatives making personal visits. Interviewers attempting to contact households for the first time (or, when returning to the sample in MIS 5, for the first time in eight months) might be less successful at finding someone at home, or have a harder time (re)establishing rapport once the household is contacted. Thus, MIS 2-4 and 6-8 typically have lower nonresponse rates than months 1 and 5. Nonresponse that varies by month would affect estimates if uncorrected, but actual CPS estimates are weighted to account for nonresponse (for further discussion of nonresponse, see CPS Technical Paper 77, Chapter 2-3).