Predicting Changes in Nasa Satellite Contracts

Six National Aeronautics and Space Administration (NASA) satellite projects containing twenty-one contracts with approximately 1,000 changes were investigated for the purpose of developing predictive models of contract change incidence which could be used for budgetary and control purposes. Of particular interest were the number, timing, and dollar amounts of changes that can be expected to occur on future contracts.

The research indicated that (1) change costs on satellite contracts have negative exponential frequency distributions, (2) contracts within the same project have the same average change costs, (3) the expected number of changes on a satellite contract is a function of the dollar size of the contract and the average project cost/change, and (4) change timing is influenced by many factors which tend to have a confounding effect on changes.

A procedure for collecting and analyzing change data and for developing suitable models is outlined. The primary limitations of the models relate to the fact that only NASA satellite contracts were involved and to the availability of a small data base for modeling.