Final answer:
The incorrect statement about focus groups is that they always involve participants who are strangers to each other. Focus groups are useful for collecting qualitative data through group discussions guided by a trained facilitator and may include participants familiar with each other, impacting the data quality.
Step-by-step explanation:
The data collection method in question here is the focus group, which has several characteristics. Contrary to one of the statements, focus groups do not always require participants to be strangers to each other. While having participants who do not know each other can reduce the impact of existing relationships on the quality of data, this is not always a feasible or necessary condition. A trained facilitator indeed asks questions to a group to gather their opinions on a topic, and the dynamic of group discussion can stimulate new thoughts on the issues at hand.
In practice, focus groups may bring together individuals who are familiar with each other. For instance, in the field of social research, they might consist of people from a certain demographic or those who share similar experiences, such as being part of a community program. As seen in the mini-case study provided, the relationship among group members, the setting, and their previous experiences can influence the responses and the range of contributions to the focus group.