There are many problems with the way most meetings are run. One of the most political is the invite list. Deciding who to include can be tough but too many managers default to including everyone. In an effort to not make anyone feel left out, they unknowingly decrease the quality of the meeting. Robert Sutton, a professor of organizational behavior at Stanford University, looked at the research on group size and concluded that the most productive meetings contain only five to eight people. Why? There is a tipping point beyond which the quality of the conversation begins to erode.