Graduation Year

2006

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Business Administration

Major Professor

Alan R. Hevner, Ph.D.

Keywords

COCOMO II, PSEstimate, Experiment, Design science

Abstract

Effective software cost estimation is one of the most challenging and important activities in software development. The software industry does not estimate projects well. Poor estimation leads to poor project planning with resulting schedule overruns, inadequate staffing, low system quality, and many aborted projects. Research on software estimation is needed to build more accurate models of the key aspects of software development. The goals of research in this dissertation are to investigate and improve the modeling of team size and project structures in current software estimation methods.Mathematical models for estimating the impacts of project team size and three variations of project structure are developed. These models accept the outputs of the COCOMO II software estimation tool, allow variation in both team size and project structure, and produce more detailed project estimates. This new extended model of COCOMO II is implemented in a decision support tool f

or software estimators called PSEstimate.Following the design science research paradigm, the artifact is evaluated with an experiment with experienced software project managers. Three treatment groups: a manual (no tool) group, a COCOMO II group, and a PSEstimate group, completed two multipart software cost estimation tasks. The accuracy and consistency of the cost and schedule estimates, the participants' confidence in their estimates, and their satisfaction with and perceived usefulness of the cost estimation tool are measured.The experimental results support most of the hypotheses of the dissertation. For most tasks, individuals aided by computer-based decision support tools produce more accurate project effort estimates and are more confident in their estimates than manual estimators. There are no significant differences between the three groups on schedule estimation. A possible explanation is that experienced estimators in the manual group compensate for the inaccuracy of th

eir effort estimates by adding time to their schedule estimates.The research contributions are new mathematical models for software estimation based on project team size and structure; a decision support tool (PSEstimate) that incorporates these models; and the experimental results that demonstrate improvements in software estimation by experienced project managers when the new models and tool are applied in practice.

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