Group discussions (also known as focus groups) normally involve between four and twelve participants and last between 30 minutes and two hours. An ideal number of participants is generally around eight. Depending on the situation, small groups of  3-4 participants can also be used, especially where we are dealing with very specialised target groups that are difficult to recruit.
The number of groups required for the exploration of a given issue can vary from two to twelve. A larger number of discussions (e.g. 20 or 30) makes evaluation remarkably complicated and therefore uneconomical.
Group discussions are primarily suited to topics that demand the kind of creative, group-dynamic process that develops when several people get together to exchange ideas and opinions. They are used, for example, in conjunction with the elaboration of a new advertising campaign, to examine the image of a brand item (such as cigarette and car brands) or to assess the acceptability of a new product.
In Zurich, Adligenswil and Geneva we have all the necessary fixed infrastructure (video recording facilities, observation suites etc.) for holding group discussions. But focus or discussion groups can also be held easily at other locations.