An Empirical Validation of the Checkpoint Software Cost Estimation Model

Abstract

As part of an on-going research project began in 1995 at the Air Force Institute of Technology, popular software cost estimation models were calibrated on data sets from a large Air Force database. The purpose was to determine if calibration improved a model's accuracy and to determine the relative accuracy of the calibrated models. The development effort accuracy of each model was evaluated before and after calibration using a hold out sample, or data not used in calibration. Results on a variety of data sets showed that calibrating the CHECKPOINT model improved its accuracy for development effort. The calibrated accuracy of the model on these data sets was significantly greater than that achieved by other calibrated models. The model's accuracy was especially noteworthy on data sets that used function points as a measure of size.