Industrial Software Metrics Top 10 List

Barry Boehm, TRW, Inc.

IEEE Software, Sept. 1987, pp. 84-85

1. Finding and fixing a software problem after delivery is 100 times more expensive than finding it and fixing it during the requirements and early design phases.

2. You can compress a software development schedule up to 25% of nominal, but no more.

3. For every dollar you spend on software development, you will spend two dollars on software maintenance.

4. Software development and maintenance costs are primarily a function of the number of source instructions in the product (which form the basis for cost models; i.e., COCOMO).

5. Variations between people account for the biggest differences in software productivity (the famous Sackman experiments).

6. The overall ratio of computer software to hardware development costs has gone from 15:85 in 1955 to 85:15 in 1985 (and the disparity is still growing).

7. Only about 15% of software product development effort is actually devoted to programming.

8. Software systems typically cost three times as much per instruction to fully develop as does an individual program. Software system products cost nine times as much.

9. Code walkthroughs will catch about 60% of the errors.

10. Many software phenomena follow a Pareto distribution:

80% of the contribution comes from 20% of the contributors.