Relating Initial Budget to Program Growth with Rayleigh and Weibull Models

Previous research on completed defense RD shows that contract expenditures can be fit well with a Rayleigh model. With fixed outlay rates, as prescribed by the OSD comptroller, the budget profile must have most of the funds in the early years to produce Rayleigh-distributed expenditures. RD programs with more delayed funding profiles may also produce expenditures that a Rayleigh model fits through schedule slips and cost overruns. This research tests how well the initial funding profile produces Rayleigh-distributed expenditures that can be related to the program's final cost overrun and schedule slips. Based only on the initial budget profile, we explain 53.4% of cost overruns and 50.5% of percent schedule slip in 37 completed programs.