The number of groups conducted usually increases with the number of participant variables (e.g., age and geographic area) of interest. Most research issues can be covered with
four to eight groups. Use of more than 10 groups seldom uncovers substantial new information on the same topic. Although some differences in opinion between participants are
desirable because they facilitate conversation, participants should be separated into different
groups when differences are likely to result in opinions being withheld or modified.
For example, including top management with middle management in the same employee focus
group can inhibit discussion. Similarly, multiple groups are used to obtain information from
different market segments. Depending on the topic being discussed, desirable commonalities among participants may include occupation, education, income, age, or gender.