Micahel, aka the Braidy Tester’s, weblog is full of insightful posts and well worth reading. In his latest post; Grading on a curve, he mentioned what he referred to as the iceberg principle. Whilst I had never heard that one before, it certainly rings true based on my experience.
The Iceberg Principle – “For every bug you find there are nine related bugs lurking close by”
Steve McConnell also supports this in Code Complete1 were he presents the following statistics:
80% of errors are found in 20% of a projects code