The selection process regarding who will be invited to participate in a focus group is actually quite simple.  Focus groups are voluntary and everyone invited has volunteered to take part in the focus group.  Focus group researchers select and invite 20-25 people with similar characteristics to a single session.  They invite a bit more than the typical 12 because not everyone who was invited will be able to attend.  Also, sometimes people do not show up to the focus groups and researchers want to make sure they have enough participants in order to gather reliable data.  Even when incentives are provided, such as refreshments, child care, or stipends, no-shows are still common, so don’t get caught short.

Having a group that has highly different characteristics can alter the quality of the data.  Individuals tend to censor their ideas in the presence of people who differ greatly from them.  To get a cross section of views it is necessary to conduct multiple sessions.  Generally people are invited to a focus group because they are alike based on certain criteria.  The next group of people will be invited based on a different criteria but it is that criterion that makes them similar.  Each focus group’s criteria and how they chose the people to be invited is based on what the focus group is about.  For example if it is a group getting people’s opinions on a brand of razor, the people invited will be ones that use that brand of razor.