Inspection saves time otherwise wasted on bug-fixing, rework and other repair activities and has been shown to make developers 20% more productive

Inspection saves time otherwise wasted on bug-fixing, rework and other repair activities and has been shown to make developers 20% more productive.

Research has yielded these findings:

An hour of inspection saves 100 hours of work. IBM found that each hour of inspection prevented about 100 hours of related work.
An hour of inspection saves 30 hours of maintenance. A study of large programs found that every hour spent on inspections avoided an average of 33 hours of maintenance.
Developers who inspect code are at least 20% more productive. Designers and programmers learn to improve their work through participating in inspections and inspections improve productivity by 20% or more.
Developers find the majority of defects when preparing for code reviews. A study of 13 reviews at AT&T found that the importance of the review meeting itself was overrated; 90% of the defects were found in preparation for the review meeting and only about 10% were found during the review itself.
Code inspection is four times more effective than testing. Microsoft's applications division has found that it takes 3 hours to find and fix a defect using code inspection compared to 12 hours by using testing.