An incentive experiment designed to increase response to a between-wave contact update mailing in two panel studies

Since 1969, the Panel Study of Income Dynamics (PSID) has sent its families a “contact update” mailing between waves of data collection in order to keep track of the whereabouts of the families and minimize attrition. Having updated contact information became all the more important starting in 1997 when PSID changed from annual to biennial interviewing. All things being equal, the longer the time between data collection waves, the greater the likelihood that sample persons have moved, and the greater the difficulty in locating movers (Couper and Ofstedal 2007; Duncan and Kalton 1987). Families are now sent the mailing the year before production interviewing, and those that update or verify their address and telephone information receive a $10 postpaid check. Field effort for the families that responded to this mailing in recent waves is much lower in the form of reduced tracking, refusal conversion efforts, and number of calls to finalize the case, underscoring the cost effectiveness of the mailing.

Given these advantages, in 2008 we designed a study to improve the response rate of the contact update mailing (McGonagle et al. 2009, in press). A main finding of that study was that response rates were substantially higher in a subgroup of nonresponding families that was sent a second mailing. The study did not provide evidence with regards to the importance of an incentive or optimal amounts for such an incentive.

This paper reports on the initial results of a second study designed in 2010 in advance of 2011 production interviewing to examine whether response rates are affected by whether an incentive is provided, and to test the relative effectiveness of different incentive amounts. Because PSID is conducted by telephone, a second outcome of interest is whether a new telephone number was provided. This study includes families that participate in the PSID, and for the first time, young adults aged 18 and older who participate in the PSID – Transition to Adulthood study (TA). TA is a panel study that follows individuals who were first interviewed as children in the PSID Child Development Supplement once they turn age 18 and collects a variety of social and economic content.