the sample of households (in the third and final stage of the sample design), one person age 15 or older is randomly selected for interview by telephone and becomes the ATUS “designated person.” Nontelephone households are contacted by mail, given a phone number, and requested to call in, with a $40 incentive that is awarded at the completion of the survey.
Lepkowski said that one of the major challenges in using the CPS as a frame for the ATUS is timing. Although most of the CPS sample becomes available to the ATUS within three months, the sample is still spread out over time due to the interviewing and processing schedule. Similar challenges related to timing have led some survey organizations to abandon second-phase samples.
Another challenge in the context of the CPS and the ATUS is that the CPS is a household survey, which must then be transformed into a person-level sample for the ATUS. Finally, it is possible that ATUS response rates are adversely affected by previous participation in several prior CPS interviews, but it is difficult to determine conclusively the potential magnitude of this effect. Overall, the telephone response rates are in the mid-50 percent range.
The second example Lepkowski described is the case of the National Health Interview Survey (NHIS) and the Medical Expenditure Panel Survey (MEPS). The NHIS is the primary source of data about the U.S. household population’s health and health care utilization. The survey is conducted by the Census Bureau and sponsored by the National Center for Health Statistics (NCHS), although other agencies also fund supplements, a situation that can be an important factor that influences an organization’s ability to share sample efficiently. The NHIS is a continuous, multistage, national probability survey with oversamples of black, Hispanic, and Asian populations. Response rates vary depending on the type of interview, generally ranging between 65 and 80 percent.
The MEPS, sponsored by the Agency for Healthcare Research and Quality (AHRQ), uses completed NHIS interviews as a sampling frame for the household component of the survey (there is also a medical provider component and an insurance component). The goal of the survey is to produce national and regional estimates of health care utilization and expenditures. Approximately 15,000 households are included annually, with occasional oversamples for additional policy-relevant subgroups. The MEPS also utilizes the oversampling performed for the NHIS. Rather than a cross-sectional design like the NHIS, the MEPS uses a panel design.
The MEPS response rates are also affected by the response rates to the NHIS. Response rates for recent NHIS surveys have typically been in the upper 80s, and the MEPS nonresponse rate is compounded by the nonresponse in the first phase. In addition, the NHIS sample sizes can vary from year to year, changing the proportion of the sample the MEPS takes from the NHIS to meet its own sample size designations.
One of the main advantages of using one survey as the sampling frame