To evaluate the effects of recent changes in welfare policy on the lives of people living at or below the poverty level, it is often necessary to survey a representative sample. As the chapter in this volume by Groves and Couper makes clear, achieving such a representative sample can be problematic both because members of low-income groups are hard to locate they are more mobile, more likely to live in multifamily households, and less likely than the more affluent to have telephones and because they may not be highly motivated to participate in surveys. Incentives especially monetary incentives are particularly useful in countering the second difficulty, as a supplement or complement to other efforts at persuasion. In this paper, we briefly consider why people participate in surveys (or fail to do so) and then review the use of incentives in counteracting certain kinds of nonresponses. We also review separately those findings that appear to be particularly relevant for low-income populations. Finally, we consider two special issues: The potential consequences of refusal conversion payments for respondents and interviewers, and the cost effectiveness of prepaid incentives.
Why Do People Participate in Surveys?
Porst and von Briel (1995) point out that although a great deal is known about survey respondents their demographic characteristics, as well as their answers to thousands of different survey questions little is known about why they choose to participate. Based on a content analysis of open-ended responses, their study of 140 participants in 5 waves of a German Methods Panel identifies 3 pure types of participants: (1) those who respond for altruistic reasons (e.g., the survey is useful for some purpose important to the respondent, or the respondent is fulfilling a social obligation 31 percent of respondents); (2) those who respond for survey-related reasons (e.g., they are interested in the survey topic, or find the interviewer appealing 38 percent); and (3) those who cite what the authors call personal reasons (e.g., they promised to do it 30 percent). In reality, of course, most people participate for a variety of reasons.
More recently, Groves et al. (2000) outlined a theory describing the decision to participate in a survey as resulting from a series of factors some survey specific, such as topic and sponsorship, others person specific, such as concerns about privacy, still others specific to the respondents social and physical environment each of which may move a particular person toward or away from cooperation with a specific survey request. Furthermore, these factors assume different weights for different persons, and they become salient for a specific individual the potential respondent when an interviewer calls to introduce the survey and request participation.
From this perspective, monetary as well as nonmonetary incentives are an inducement offered by the survey designer to compensate for the relative absence of factors that might otherwise stimulate cooperation for example, interest in the survey topic or a sense of civic obligation. Although other theoretical frameworks such as social exchange theory (cf. Dillman, 1978), the norm of reciprocity (Gouldner, 1960), and economic exchange (e.g., Biner and Kidd, 1994) also can be used to explain the effectiveness of incentives, the present perspective is able to account for the differential effects of incentives under different conditions (e.g., for respondents with differing interest in the survey topic or with different degrees of community activism) in a way that other theories cannot easily do.
Incentives and Hard-to-Reach Populations
As indicated above, members of a group may be hard to interview both because they are difficult to locate or to find at home and because they have little motivation to participate in a survey. There is no empirical evidence that incentives are helpful in overcoming the first problem in a random digit dial (RDD) survey, nor any theoretical justification for believing that they would or should be. Thus, if the primary problem is one of finding people at home for such a survey, incentives may not be very useful. However, an experiment by Kerachsky and Mallar (1981) with a sample of economically disadvantaged youth suggests that prepayment may be helpful in locating members of a list sample, especially in later waves of a longitudinal survey. One reason, apparently, is that prepayment (and perhaps promised incentives from a trusted source) may be useful in persuading friends or relatives to forward the survey organizations advance letter or to provide interviewers with a current telephone number for the designated respondent.
The remainder of this chapter is devoted to reviewing the evidence pertaining to the second reason for survey nonresponse namely, the situation in which the respondent has little intrinsic motivation to respond to the survey request. This situation is likely to characterize many low-income respondents, especially those who no longer receive welfare payments because of changes in federal and state legislation. Hence, the findings reported in this chapter about the effectiveness of prepaid monetary incentives are especially likely to apply to this population.