Did You Know That:
1. Testing/debugging can worsen reliability
- Each correction had a 15% chance of creating a problem as large as the problem it was supposedly fixing [Ed Adams, IBM, 1984]
2. We often chase the "wrong bugs"
- 33% of all faults failed less than once in every 5000 execution years
- 2% of all faults caused the common failures (more than once every 5 execution years)
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3. Testing cannot show the absence of faults, but can show the existence of faults [Dijkstra]