Monday, June 20, 2016

Even The Best Surveys Have Problems

Just how accurate are even the best surveys—the federal government's Current Population Survey, for example. The CPS is the source of vital economic indicators such as labor force participation and unemployment. Do the rates it measures reflect reality?

A National Bureau of Economic Research analysis examines this question, analyzing some of the basic indicators measured by the CPS, the Consumer Expenditure Survey, and the Behavioral Risk Factor Surveillance System. The goal of the analysis was to determine how much certain indicators vary depending on the number of times survey interviewers attempt to contact respondents. Disturbingly, the indicators vary quite a bit. The labor force participation rate is lower, for example, among participants who respond on the first attempt and higher for those who require three or four attempts before participating in the survey—even after controlling for demographic characteristics. The labor force participation rate was just 63.0 percent among respondents reached on the first attempt and climbed to 72.3 percent among respondents who could be reached only after three or four attempts. The unemployment rate was higher among those reached on the first attempt (8.1 percent) than among harder-to-reach respondents (6.7 percent). The researchers found similar troubling variations in measures produced by the other two surveys: household spending (Consumer Expenditure Survey), and obesity (Behavioral Risk Factor Surveillance System).

How much do our important socioeconomic indicators reflect reality and how much are they a function of who is easiest to reach? What about those who can't be reached after multiple attempts? The authors of the study are concerned.

Source: National Bureau of Economic Research, Difficulty to Reach Respondents and Nonresponse Bias: Evidence from Large Government Surveys, Working Paper 22333 ($5)

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