> In programming specifically, many studies have shown order of magnitude differences in the quality of the programs written, the sizes of the programs written, and the productivity of the programmers. The original study that showed huge variations in individual programming productivity was conducted in the late 1960s by Sackman, Erikson, and Grant (1968). They studied professional programmers with an average of 7 years' experience and found that the ratio of intitial coding time between the best and worst programmers was about 20:1; the ratio of debugging times over 25:1; of program sizes 5:1; and of program execution speed about 10:1. They found no relationship between a programmer's amount of experience and code quality or productivity. (Code Complete, page 548)
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