Editor's note: Mark Goodin is president of Aaron-Abrams Field Support Services, a Las Vegas research company. 

The number of people willing to spend time participating in qualitative research is shrinking. Many are even refusing to take calls from recruiters these days. That's why researchers must take steps to keep our respondent pool well-stocked with quality individuals.

Following are four ways in which market researchers can protect the respondent pool and help ensure the long-term health of qualitative research:

1. Streamline your screening process.
Respondents have grown weary of lengthy screening questionnaires. A seemingly endless barrage of questions invites respondent fatigue, and they simply zone out. Respondents who don't give 100 percent of their attention to recruiters may incorrectly qualify for your research. How long should it take to administer a screening questionnaire? Based on our experience, we suggest under 10 minutes.
2. Make it easier for respondents to qualify.
Most respondents who fail to pass the screening process tell us that they believe they are actually answering survey questions, but without being compensated. As a result, the next time a recruiter calls, these respondents won't answer because they don't want to "work for free." Long screening questionnaires and numerous failed recruitment attempts sour respondents against market research and shrink the respondent pool.

3. Offer adequate incentives.
Many researchers offer respondents a "fun and exciting time" in lieu of a proper incentive. If you truly want to offer respondents a fun and exciting time, send them to Magic Mountain or Disneyland. Respondents are acting as consultants for you when they participate in your research, and they therefore deserve suitable compensation. Attractive incentives not only help ensure that your respondent pool will remain well-stocked, but they also raise respondent cooperation rates.

4. Choose convenient research times.
Most people are employed during the day and are not available to do research during working hours. In addition, not everyone wants researchers in their homes or tagging along to the grocery store. People lead busy lives, and they're concerned about their right to privacy. When attending your research is inconvenient, respondents will say no. And if you repeatedly offer inconvenient research times, respondents will opt out of the respondent pool all together.

Makes sense

The bottom line is that one of the reasons that qualitative research has seen a sharp increase in the number of cheaters, repeaters and other problem respondents is that many quality respondents have become frustrated with market research and simply don't want to bother. What you're left with often are respondents who participate solely for the money. What's more, a shrinking respondent pool means higher prices for all of us. So keeping the pool stocked with quality respondents makes sense - both now and in the future.