Are Advanced Postcards or Letters Better? An Experiment with Advance Mailing Types

Abstract

Busy survey shops struggle daily to figure out the most methodologically sound approach that fits within clients’ (often limited) budgets. Many projects require innovative techniques even with basic practices, such as advance notification. Sending advance (or prenotification) letters prior to a call or survey helps to increase response rates (De Leeuw et al. 2007; Dillman et al. 1976), but does the type of mailing matter as well? In this article, I compare the results of an advance postcard versus an advance letter, and find that overall letters are the more cost-effective option. Hembroff et al. (2005) established that the format of advance notification (letter versus postcard) matters insofar as advance letters tend to increase response rates more than advance postcards, which in turn reduces the overall survey costs. Obtaining a higher response rate is a desired outcome of most survey research projects because of concern with nonresponse (Groves 2006). Even if both types of advance mailings increase the overall response rate, if there is differential response by subgroups, then this raises concerns about nonresponse bias. To evaluate differential response by mail type, I examined responses to key demographic variables by mailing type. In addition, Dillman et al. (2009) hypothesize that higher response rates achieved from an advance letter versus a postcard are due in part to respondent recall. Therefore, it is also important to determine if recall is different by advance mail type. Hembroff et al. (2005) provide a detailed account of costs by mailing type, but for some cost-incurring items the researchers relied on estimates rather than real costs. Accordingly, we still need a detailed understanding of actual costs incurred by each mailing type, relative to the response rate. Can clients save money and maintain sufficient response rates using postcards instead of letters?