Focus groups come in two primary forms. Concept focus groups are less rigidly structured and resemble a brainstorming approach to developing themes for trial. This approach is akin to the discovery phase of trial preparation, and is most often used in that time frame of the case development. Structured focus groups involve a set presentation, usually of facts and argument that are anticipated at the time of trial. Structured groups, like mock trials, are also helpful for the trial team in that to do them well requires thorough consideration of what the themes and strategies of the opposition will be. The length of the group sessions, as well as the size and number of groups to be run, are areas of flexibility. The very thorough report of the groups examines the value and impact of each element of the presentation, as well as addressing specific questions and issues of concern about the cases.