Size of Incentive Effects in a Longitudinal Study

This paper describes an experiment conducted
as part of one wave of the Health and Retirement
Study (HRS), which is a longitudinal survey of a
nationally representative sample of persons who
were born in 1947 or before. Interviews have been
conducted biennially since 1992. The general
practice, after wave 1, has been to include a check
for $20 along with an advance letter sent to each
sample member prior to their being contacted, by
telephone or face-to-face, by an interviewer. The
experiment consisted of changing the amount of
the incentive check for randomly selected sample
members, with the objective of examining the
effect of incentive size in the response rate, on the
amount of effort required to finalize the case, and
the quality of the data obtained from respondents.
In this paper, we examine the effects of the size of
the incentive on the response rate on the immediate wave, and also briefly examine the effects on
the number of calls.