The author suggests that programmers vary in talent by reliability, buglessness, extensibility and maintainability. He goes on to suggest that these are hard to

The author suggests that programmers vary in talent by reliability, buglessness, extensibility and maintainability. He goes on to suggest that these are hard to measure. "It's not that good developers can churn out 10 times as many features as the bad ones. It's rather that good developers write code that have less bugs, more extensible and more maintainable. These are the things that you can't measure by statistics or figures." I've given a few examples of good developers making systems that are orders of magnitude harder to complete, in the same time. In many cases it's not within the current talents of most programmers to write those systems at all. Another good example is the Quake engines. Additionally, in programming contests or student assignments there are many examples of people completing the same task in vastly different amounts of time. Finally, he states that reliability, buglessness, maintainability and extensibility are things you can measure with statistics, but many people have quantified uptime, maintenance, density-of-bugs, and extension time, to moderate success.