An exploratory research group of 8 to 12 participants, led by a moderator, who meet for an in-depth discussion on one particular topic or concept. The participants are generally chosen for their relevance to the particular topic or concept. By skilful use of probes and other interviewing devices, the group members are encouraged to respond in depth to the moderator. These group discussions largely depend for their success on the moderator, who must establish the right atmosphere in order to gain the maximum involvement and cooperation of all the group members. Focus groups are useful in the early stages of developing methods to understand the nature of business or organizational problems and for suggesting issues that should be covered in a questionnaire survey. Discussions are usually recorded and observed through see-through mirrors (with the full knowledge of the group members). Normally, these groups last for between one and three months.