The intuition underlying the Henderson-Sellers method of calculating Lack of Cohesion of Methods (LCOM) is that in a cohesive class C, many methods access the same fields of C. Formally, let

• M = set of methods in class
• F = set of fields in class
• r(f) = number of methods that access field f
• ar = mean of r(f) over f in F

We then define LCOM of the class under consideration to be

LCOM = (ar - |M|) / (1 - |M|)

We follow Lance Walton (author of the State of Flow Eclipse Metrics Plugin) in restricting M to methods that read some field in the same class, and F to fields that are read by some method in the same class.

A value greater than 0.9 indicates a class that may deserve some further scrutiny.

References

Brian Henderson-Sellers. Object-Oriented Metrics: Measures of Complexity. Prentice-Hall 1996.

Frank Sauer. Metrics 1.3.6 - Getting Started. 2005.

Renaat Verbruggen. Object-oriented patterns and metrics (Lecture Notes). (updated regularly)

Lance Walton. Eclipse Metrics Plugin. State of Flow, 2005.