Data accuracy: how good are our usual indicators?

This paper discusses in detail issues dealing with the technical aspects of designing and conducting surveys. Its is intended for an audience of survey methodologists.

In 2000, the Behavioral Risk Factor Surveillance System (BRFSS) conducted monthly telephone surveys in 50 American states, the District of Columbia, and Puerto Rico: each was responsible for collecting its own survey data. In Maine, data collection was split between the state health department and ORC Macro, a commercial market research firm. Examination of survey outcome rates, selection biases and missing values for income suggest that the Maine health department data are more accurate. However, out of 18 behavioural health risk factors, only four are statistically different by data collector, and for these four factors, the data collected by ORC Macro seem more accurate.