Data collection frequency effect in the National Medical Care Expenditure Survey.

The National Medical Care Expenditure Survey (NMCES) was characterized by a longitudinal survey design, with data collection targeted to five points in time covering the survey year. Field conditions did not allow for all interviews to be conducted over the targeted time periods. A subset of sampled households (holdovers) were not contacted for a particular wave of the survey and data were gathered at the subsequent time period for the two time intervals that were spanned. National estimates for a representative set of health care utilization and expenditure measures were derived from the sample of holdovers and compared with estimates derived from the respondents with five complete waves of data collection. Controlling for relevant predispositional factors in the estimation of health care utilization and expenditure measures, a test for data collection frequency effect is also considered.