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Cost estimation, topics Quantitative models (E = 2.5 KLOC1.05) Qualitative models (e.g. expert estimation) Agile cost estimation Relate cost to development time SE, Cost estimation, Hans van Vliet, ©2008 2 On productivity Even if quantitative models are not that good, the cost drivers of these models learn us about productivity: Writing less code helps Reuse helps Quality of people is important Tools help … SE, Cost estimation, Hans van Vliet, ©2008 3 Algorithmic models Base formula: E = a + bKLOCc C usually is around 1 C > 1: diseconomy of scale C < 1: economy of scale This nominal cost is multiplied by a number of cost drivers (volatility of requirements, amount of documentation required, CMM level, quality of people, …) SE, Cost estimation, Hans van Vliet, ©2008 4 Walston-Felix One of the early algorithmic models (1977) Many factors (29 out of 51 projects) Only three alternatives (high, medium, low) per factor Its form influenced many later models SE, Cost estimation, Hans van Vliet, ©2008 5 COCOMO (COnstructive COst MOdel) Very well-documented (Boehm book, 1981) Basic form: E = bKLOCc, where b (~3) and c (1+ε) depend on the type of project (mode): Organic: relatively small and well-known Embedded: inflexible environment with many constraints Semidetached: somewhere in between More complex form: takes into account 15 multiplicative cost drivers SE, Cost estimation, Hans van Vliet, ©2008 6
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