As little as two decades ago, leading researchers would only offer an incentive in surveys where the interview length was more than 45 minutes. How times change! Today, response rates for even the best designed and managed surveys are dropping and using incentives is commonplace. However, there is still debate about when to use incentives, what kind of incentive to use, and the impact of offering incentives on data quality.
To start, let’s consider why people respond to surveys. Research has consistently identified four main reasons:
- Altruism (wanting to be helpful to the researcher or society)
- Interest in the research topic
- Perceived self-benefit (i.e., by responding to survey, products or services will improve)
- Direct incentives
You can’t depend on the good will of respondents and often it is necessary to conduct surveys among respondents with low interest and weak perceived benefits. So, earning incentives is an important reason for completing surveys for some portion of the population. Therefore, it stands to reason that offering survey incentives will increase response rates. And, through research conducted by Church, Edwards and others (and summarized here), the following “truths” or guidelines have become standard:
- Prepaid incentives (included with the survey) yield higher response than no incentives or incentives paid after survey response, for all types of surveys
- Money yields higher response rates than merchandise
- Response rates increase as the amount of money paid increases, but not linearly and with a decreasing rate of impact
- Small, individual incentives work better than drawings or sweepstakes for a chance to win a larger incentive
Okay, incentives increase response rate. Marketers still struggle with the decision to offer incentives, with these objections:
- But doesn’t offering incentives have a negative impact on data quality? Again, many researchers have looked into this and found no support that data quality decreases with incentive. Indeed, some of these studies show that data quality might even improve with incentives. For example, in a customer satisfaction study, a sample of respondents without incentives may be skewed to dissatisfied customers who perceive that they have a stake in the results. By offering incentives, you may get a more balanced sample of customers, including those without an ax to grind.
- But won’t they make the research too expensive? Researchers must balance the cost of incentives against the overall cost of the research project, as well as the value of the information that will be received. If incentives increase the response rate, they may decrease the amount of raw sample needed, which may somewhat offset the additional cost. Even if the only benefit of offering incentives is to make managers more comfortable with acting on the resulting data, that may be a reason for incentives.
- But do incentives increase response rate enough to justify the additional cost? Unfortunately, although the amount of increase in response rates has been extensively researched, there is no definitive answer to this question. Study results range from minimal (but significant) increases to more than doubling the response rates. The fact is that other factors (e.g., the survey topic, the nature of the sample, sample source, survey length, etc.) also impact response rate. Therefore, researchers have not been able to isolate the impact of offering incentives on increasing response rates.
There has been some research into offering the incentive only for non-responders. For example, the incentive would only be offered to those respondents who first refuse participation (or non-responders to an online survey) or only for respondents who are under-represented in the results. Research results for this practice are inconclusive. Additionally, the practice is criticized as being “unfair” to those respondents willing to participate without an incentive.
The use of incentives in survey research has been shown to be a positive influence overall. And today, regardless of survey length, some incentive is nearly always included. (Of course, if you are using panel sample, you don’t have a choice as panels incent their members for participating in all surveys.) Some researchers argue that we, as an industry, have “taught” the public that they should expect to be paid for their time and opinions. Nonetheless, the fact remains that incentives will increase response rate. If you are struggling to get completions, next time offer an incentive and see if it makes a difference.