5.3 Personnel Factors


5.3 Personnel Factors

Personnel factors also exert significant influence on project outcomes. According to Cocomo II, on a 100,000-LOC project the combined effect of personnel factors can swing a project estimate by as much as a factor of 22! In other words, if your project ranked worst in each category shown in Figure 5-6 (shown by the gray bars), it would require 22 times as much total effort as a project that ranked best in each category (shown by the blue bars).

image from book
Figure 5-6: Effect of personnel factors on project effort. Depending on the strength or weakness in each factor, the project results can vary by the amount indicated—that is, a project with the worst requirements analysts would require 42% more effort than nominal, whereas a project with the best analysts would require 29% less effort than nominal.

The magnitude of these factors from the Cocomo II model is confirmed by numerous studies since the 1960s that show 10:1 to 20:1 differences in individual and team performance (Sackman, Erikson, and Grant 1968; Weinberg and Schulman 1974; Curtis 1981; Mills 1983; Boehm, Gray, and Seewaldt 1984; DeMarco and Lister 1985; Curtis et al. 1986; Card 1987; Boehm 1987b; Boehm and Papaccio 1988; Valett and McGarry 1989; Boehm et al. 2000).

One implication of these variations among individuals is that you can't accurately estimate a project if you don't have some idea of who will be doing the work—because individual performance varies by a factor of 10 or more. Within any particular organization, however, your estimates probably won't need to account for that much variation because both top-tier and bottom-tier developers tend to migrate toward organizations that employ other people with similar skill levels (Mills 1983, DeMarco and Lister 1999).

Another implication is that the most accurate estimation approach will depend on whether you know who specifically will be doing the work that's being estimated. That issue is discussed in Chapter 16, "Flow of Software Estimates on a Well-Estimated Project."




Software Estimation. Demystifying the Black Art
Software Estimation: Demystifying the Black Art (Best Practices (Microsoft))
ISBN: 0735605351
EAN: 2147483647
Year: 2004
Pages: 212

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