Effective OO designs maximize cohesion because they promote encapsulation. Average the percentages, then subtract from 100 percent. Lower percentages indicate greater data and method cohesion within the class. Methods are more similar if they operate on the same attributes. Count the disjoint sets produced from the intersection of the sets of attributes used by the methods.
High cohesion indicates good class subdivision.
Lack of cohesion or low cohesion increases complexity, thereby increasing the likelihood of errors during development. Classes with low cohesion could probably be subdivided into two or more subclasses with increased cohesion. Classes are coupled when methods declared in one class use methods or attributes from the other classes. Inheritance introduces significant tight coupling between superclasses and their subclasses. Since good OO design requires a balance between coupling and inheritance, coupling measures focus on non-inheritance coupling.