Reducing software defects: 10 things to keep in mind

I’ve been involved with software development for over 12 years now. Over that period I’ve been a developer, architect and a project manager in different software projects. So the following list of 10 things relating to software development (and the key issue of software defect reduction) made a lot of sense.

  1. Finding and fixing a software problem after delivery is often 100 times more expensive than finding and fixing it during the requirements and design phase.
  2. About 40-50% of the effort on current software projects is spent on avoidable rework.
  3. About 80% of the avoidable rework comes from 20% of the defects.
  4. About 80% of the defects come from 20% of the modules and about half the modules are defect free.
  5. About 90% of the downtime comes from at most 10% of the defects.
  6. Peer reviews catch 60% of the defects.
  7. Perspective-based reviews catch 35% more defects than non-directed reviews.
  8. Disciplined personal practices can reduce defect introduction rates by up to 75%.
  9. All other things being equal, it costs 50% more per source instruction to develop high-dependability software products than to develop low-dependability software products. However, the investment is more than worth it if significant operations and maintenance costs are involved.
  10. About 40-50% of user programs enter use with nontrivial defects.

More on each of these points can be found in this expanded article entitled, Software Defect Reduction Top-10 List, by Barry Boehm, USC and Victor Basili, U. of Maryland.

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