The goal of most research on group development is to learn why and how small groups change over time. To do this, researchers examine patterns of change and continuity in groups over time. Aspects of a group that might be studied include the quality of the output

Output

Output is the term denoting either an exit or changes which exit a system and which activate/modify a process. It is an abstract concept, used in the modeling, system design and system exploitation.-In control theory:...

 produced by a group, the type and frequency of its activities, its cohesiveness, the existence of group conflict

Group conflict

Group conflict, or hostilities between different groups, is a pervasive feature common to all levels of social organization .. Although group conflict is one of the most complex phenomena studied by social scientists, the history of the human race evidences a series of group-level conflicts that...

.

A number of theoretical models

Scientific modelling

Scientific modelling is the process of generating abstract, conceptual, graphical and/or mathematical models. Science offers a growing collection of methods, techniques and theory about all kinds of specialized scientific modelling...

 have been developed to explain how certain groups change over time.