But a small, dedicated group of study participants can also raise problems for researchers who seek a representative sample in their data. If the same group of individuals are participating in studies on a regular basis, that can raise questions about data integrity.

According to Psychology Department Study Pool Coordinator Janet Smith, researchers highly encourage undergraduate participation in pools because it broadens and diversifies data. However, the department discourages and tries to prevent one participant from taking too many studies because it can damage data validity.

That is a big part of why many schools cap the number of studies one subject can participate in during a year.

“The more people we have participating the better the data will be,” Smith said. “That is true with any kind of research. If you do a study with 500 people rather than five, you’re going to get better data because you have better sampling.”

Sometimes individuals try to get around the 15 study limit or do not pay close attention to the study requirements, she said.

“It’s better for all of us if people follow the rules,” Smith said. “It would really help us if people take a look at the rules. The rules we have help protect the data.”

But for students, the flexibility of the job can also come with inconsistency.

Studies are offered during most hours of the work day and students may sign up for them up to 24 hours in advance, allowing the system to accommodate virtually any schedule. But since studies are not scheduled everyday and have limited enrollment, it can be challenging to always find a suitable time slot, which can make it difficult to rely on study participation as a steady source of income.

“Sometimes, there are no studies one week and a ton the next week,” said Sarah Hirschfeld-Sussman, Laboratory Manager at the Decision Science Laboratory. “With a library job, there is a lot of consistency, but with us, it’s a little more risky.”

Despite these risks, Hirschfeld-Sussman says that the nature of the studies serves as an incentive for undergraduates to participate.

“It’s fun and it’s different,” Hirschfeld-Sussman said. “Every time you come it’s a completely different study. Sometimes, you get results about yourself, your behavior, and how you make decisions.”

Students echo Hirschfeld-Sussman’s assertions and say that participating in studies can be a more enjoyable experience than working a desk job.

“I think some of them are pretty interesting to do and a more fun way to make money,” said Angela C. Li ’14, who frequents studies at the Psychology Department. “They have you do pretty interesting things, but also I’ve read a lot about psych studies, and it’s really nice to be on the other side of it.”

—Staff writer Patrick Galvin can be reached at pgalvin@college.harvard.edu.