When conducting a focus group, or even an in-depth interview (IDI), there are a lot of factors that can derail the proceedings. Respondents could be fakers (i.e., lying during the screening process), late, inebriated, offensive, dominating, or simply quiet. All of these issues have to be dealt with by a qualified and experienced moderator.
However, even when the respondent is fully qualified, sober, respectful, and communicative, another issue can arise that is rather insidious. That is when a respondent is more interested in something else besides the topic being discussed.
One can hardly blame them sometimes. It is a challenge to make mayonnaise interesting for 2 hours. Nevertheless, they should at the very least want to talk about the subject at hand.
For example, some respondents can feel pressured by their peers, even if the others in the room are perfectly polite and even encouraging. This is most common among college students and young adults (about 20-27 years of age). Perhaps they are still developing a sense of self. Perhaps they are attracted to someone in the group. Perhaps one person reminds him/her of a bully. Perhaps a lot of things, but often respondents at about this age (but certainly not only at that age) are very hesitant to give honest, personal answers to questions. I remember when a college-aged respondent gave an answer, a second respondent said that he disagreed, and then the first respondent immediately and completely changed his answer.
Another example are those types of respondents that are trying to impress. They can be flirting with another respondent (or even with the moderator), feel the need to correct other respondents in case they mistaken about some fact/issue, or to convince them to see things in a particular way. I have had to find ways to make respondents not feel awkward, deflecting what can be unwanted advances, or even handling such comments directed towards me.
(As a quick note, sometimes it is best not to correct something factually wrong said by the respondent as it indicates the knowledge level present in the marketplace.)
No single solution will resolve all of these issues. Obviously, one can politely stop extraneous comments before and when they become a distraction. (e.g., “Fair enough but remember that we are here to discuss [TOPIC]”). That being said, allowing a few tangents here and there can actually be helpful in creating rapport within the group, so long as they are appropriate and in the proper amount.
A more overarching solution is to remind respondents why they are in the focus group (e.g., “Fair enough but remember that we are here to discuss [TOPIC]”). At the very least, it keeps the topic of the discussion in the forefront of their mind.
I also find it helpful, especially among younger respondents to orientate them again to what a focus group actually is and what types of answers are sought (emotions, associations, experiences, opinions, etc.). Reminding them that that there really isn’t a right or wrong answer, that everything is confidential, you want that “weird” answer that they might think is silly, can sometimes push them past any shyness or social pressures they might feel. It can also help re-center the group in case responses are getting too off-topic or distracting.