COCOMO allows the estimator to use 15 different drivers which may impact the cost. These drivers can be specified in one of six available ratings: very low, low, nominal, high, very high and extra high. Not all ratings are available for all cost drivers. For example, for the “Programming language experience” cost driver, the model allows only very low, low, nominal, and high ratings.
Behind these ratings, there are particular values (multipliers) that affect the final cost of the project. These values were calculated based on the original 63 projects and can be modified to adjust to, for example, a different Function Points method used for software sizing (read below).
Piotr Pozniak