From Nielson Norman Group: https://www.nngroup.com/articles/screening-questions-select-research-participants/
Summary: To recruit appropriate UX research participants, assess people’s characteristics without giving away the purpose of the study.
Finding the right participants for a user-research study can be challenging, even if you have clearly defined your target audience . You can learn something from almost any user, but you’ll get more meaningful insights if your study participants have the same behaviors, interests, and knowledge as your actual users.
Using Screening Questions to Select Participants
To recruit study participants, you should ask screening questions which assess their background and characteristics. For example, if you’re designing a website about online games, you might need people who are interested in gaming. To assess this, you could simply ask them, “Do you play online games?”
But screening questions that make the purpose of the study obvious can backfire. If people can easily guess what the study is about, some will be tempted to exaggerate their responses just so they can participate (and receive the incentive, if the study offers one). When part of the screening process for a research study, the question “Do you play online games?” will clearly signal to respondents that the study is about gaming. It will be easy for people to guess that, if they admit that they do not play online games, they’re unlikely to be invited to participate in the study.
