The objective of this study is to evaluate the predictive validity of the Capability Maturity Model (CMM) for Software (SW-CMM) as applied to software maintenance.

The SW-CMM is intended to apply to both software development and maintenance. A basic premise (hypothesis) of the SW-CMM is that improving process maturity will result in better project performance and product quality. The extent to which that hypothesis is supported empirically is called a test of its predictive validity. No previous evaluation exists of the predictive validity of the SW-CMM in a maintenance context.

The extent to which schedule estimates differ from reality is one important measure of project performance. But is higher maturity in fact correlated with a reduction in schedule deviation? Data from 752 maintenance projects drawn from 441 SW-CMM assessments are analyzed using a zero inflated Poisson (ZIP) regression model, and the results are validated using a bootstrap estimation method. Projects from higher maturity organizations typically report less schedule deviation than those from organizations assessed at lower maturity levels.