Regression Models of Software Development Effort Estimation Accuracy and Bias

  • Authors:

  • Magne Jørgensen

  • Affiliations:

  • Simula Research Laboratory magne.jorgensen@simula.no

  • Venue:
  • Empirical Software Engineering
  • Year:
  • 2004

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Abstract

This paper describes models whose purpose is to explain the accuracy and bias variation of an organization’s estimates of software development effort through regression analysis. We collected information about variables that we believed would affect the accuracy or bias of estimates of the performance of tasks completed by the organization. In total, information about 49 software development tasks was collected. We found that the following conditions led to inaccuracies in estimates: (1) Estimates were provided by a person in the role of “software developer” instead of “project leader”, (2) The project had as its highest priority time-to-delivery instead of quality or cost, and (3) The estimator did not participate in the completion of the task. The following conditions led to an increased bias towards under-estimation: (1) Estimates were provided by a person with the role of “project leader” instead of “software developer”. (2) The estimator assessed the accuracy of own estimates of similar, previously completed tasks to be low (more than 20% error). Although all variables included in the models were significant p