Extended field efforts to reduce the risk of non-response bias : do they pay off?

We examine the effects on survey estimates of extended interviewer efforts to gain survey response, including refusal conversion attempts and attempts to make contact with hard-to-contact sample members. Specifically, we update and extend the research of Lynn & Clarke (2002). We estimate bias reduction for demographic and substantive variables from the Health Survey for England, the British Social Attitudes Survey, and the Family Resources Survey and we assess change over a ten-year period. We consider a more precise measure of the difficulty of contact, which was not available to Lynn & Clarke, and we assess the effect of extended efforts on weighted estimates. -- interviewers ; non-contact ; non-response ; refusal