Evaluating Key Statements Analysis

Key Statement Analysis extracts from a program, statements that form the core of the program’s computation. A good set of key statements is small but has a large impact. Key statements form a useful starting point for understanding and manipulating a program. An empirical investigation of three kinds of key statements is presented. The three are based on Bieman and Ott’s principal variables. To be effective, the key statements must have high impact and form a small, highly cohesive unit. Using a minor improvement of metrics for measuring impact and cohesion, key statements are shown to capture about 75% of the semantic effect of the function from which they are drawn. At the same time, they have cohesion about 20 percentage points higher than the corresponding function. A statistical analysis of the differences shows that key statements have higher average impact and higher average cohesion (p≪0.001).