For every research project, you have to find the right users who will most likely tell you what you want to learn.
Even if you have a ready-made list of customers that use your product, you still have to find the right users within that customer group.
I usually do a screener as part of the overall test plan. The screener for most rapid user research can be a list of attributes that the users must have or what mix of user types are needed for the study.
Quick participant screener
In a quick screener, I only do a set of bullet points describing the criteria a participant must meet to qualify for the research. While there is still a lot of thought that goes into these short lists of criteria and they are quickly understood by team members, I still believe that longer, informal screeners result in better recruits. But a quick screener is great for quick, regular regular such as what is done in Agile sprints.
A formal screener is great when you are outsourcing the recruiting of participants to a professional recruiting firm. Since it’s more of a script, it shows EXACTLY what to ask and when and helps to verify that the people you are screening are really telling you the correct answers and truly meet the recruiting criteria. Formal screeners also force the research team to really think about every nuance of the study.