Best Case/Worst Case is a planning model. As a DesignTeam assignment, it can be designed as a Scan process or a Focus process. As a Scan process, it's typically a variation or extension of the Scenario exercise: one team (or more) is assigned to write a "Best Case" scenario of internal/external conditions and events; another is assigned to write a "Worst Case" Scenario; and another (optionally) to write a "Probable Case" Scenario. As a Focus assignment, this is an exercise in contingency planning; the same scenario information (internal/external conditions) may be generated, yet here the emphasis is on designing the (proposed) optimal group response(s) to each contingency.

This is a modeling exercise. As always, the parameters chosen for each model have to be useful. Participants should be directed to avoid "Best Case" and "Worst Case" predictions that are so extreme that they are meaningless. For example, thermonuclear war may indeed be a worst case scenario, but it "changes the game" so radically that few organizations would find it worth their time to invent meaningful response.