Methods for Modeling Computer Based Systems are evaluated against a common generic model. A formal Entity-Relationship (ER) model is used to compare the expressive power of methods. Expressive power is important as statements that cannot be expressed in a model will be omitted from the analysis and resulting specification. Methods are also analyzed to determine whether they are based on a partial order temporal approach rather than a linear or branching approach. (Partial order is the most powerful of the temporal approaches.) In addition, methods are judged with respect to fifteen method characteristics such as comprehension and support for reuse.