How much to pay research participants based on study length, content and incentive type

Editor's note: Ian Floyd is the Head of Research and Insights at Tremendous.

Considering extending your study or survey? That may be less expensive than you think. According to our latest research, surveys become cheaper minute per minute as they get longer. 

We partnered with The Decision Lab (TDL), an applied research and innovation firm specializing in human behavior, to determine exactly how much researchers should be paying participants based on length of study, the content of the research itself and incentive type. 

Existing research on how much to pay research participants is typically descriptive – it lays out best practices based on rates researchers typically pay, rather than on how participants want to be paid. Our research is different. Using a series of discrete choice experiments, we discovered how participants expect and want to be paid, as well as how they respond to different kinds of incentives. 

As a result, we were able to determine:

• When researchers are overpaying participants.
• When researchers are underpaying participants.
• How changes to the length and content of your research, as well as the incentive that comes with it, affect how much participants expect to be paid.

Long studies and surveys get cheaper by the minute

Participants, naturally, expect to be paid more for a 15-minute survey than for a five-minute survey. We found, on average, research participants expect to be paid about $17.62 more for a research task taking 15 minutes than a five-minute one. 

Interestingly, though, we found that the longer your experiment or study runs, the cheaper each additional minute becomes. 

For example: 

• Say you’re increasing the length of your study from five to 15 minutes. For these 10 additional minutes, each minute will cost you $1.76. 
• Now, say you increase the length of your study from 15 to 30 minutes. The price of each additional minute is now $1.44. 
• Finally, say that instead of 30 minutes, you decide to boost your interview time to an hour. Now, each additional minute will cost only $0.71. 

While some researchers may worry about how increasing study length will impact participant motivation, it’s pretty inexpensive to include additional questions while still fairly compensating respondents. 

Studies that require human interaction are more expensive

Research participants, overall, prefer studies that don’t require them to interface with another person. Consequently, people prefer online surveys over online interviews. 

According to our research, participants expect about $8.66 more for an online interview compared to a survey. 

Similarly, studies that probe into personal topics are also a bit more expensive than relatively surface-level inquiries.

However, if your study is short, you may not have to worry about the sensitivity of the topic. 

• For surveys that are between five and 40 minutes long, the cost of a sensitive discussion and a surface-level discussion are almost equal.
• For surveys that are an hour or longer, the content of the discussion matters: Sensitive topics cost $9 more than less privileged information. 

Cash is king

Overwhelmingly, research participants view cash as the most valuable incentive type. 

Specifically, cash is at least $9.50 more valuable to participants than any other incentive type. 

Comparatively: 

• Mailed checks need to be $13.37 larger to be perceived as equally valuable as cash.
• Prepaid Visa cards are the next best option, largely because of their flexibility. 
• Finally, gift cards of the participants’ choice are the third-most valuable option to consumers. They’d prefer to choose their own gift card rather than receive an Amazon gift card. 

Conducting studies and surveys about less-sensitive topics, and thanking participants with cash, will likely be the best bang for your buck. 

This is just a cursory look at our findings. For a complete analysis of our research, head to tremendous.com on October 1. 

tremendous.com