A Procedure for Assessing the Influence of Problem Domain on Effort Estimation Consistency

  • Authors:
  • John Moses;Malcolm Farrow

  • Affiliations:
  • School of Computing and Technology, University of Sunderland, SR6 0DD, UK;School of Computing and Technology, University of Sunderland, SR6 0DD, UK

  • Venue:
  • Software Quality Control
  • Year:
  • 2003

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Abstract

By and large, given the inherent subjectivity in defining and measuring factors used in algorithmic effort estimation methods, when algorithmic methods produce consistent estimates it seems reasonable to assume that this is in part due to estimator experience. Further, software development factors are usually assumed to have different degrees of influence on actual effort. For example, no specific allowances for program language or problem domain were made in the original COCOMO model or in Albrecht's Function Points, whilst allowances for development mode in COCOMO and function type complexity for Albrecht's Function Points are crucial. However, work has been conducted that concluded that 4GLs are associated with higher productivity than 3GLs. Clearly, we can support such conclusions about productivity, since, for example, it usually requires less effort to develop a database using a purposely designed DBMS product than it does using a 3GL. However, in general, for a given problem domain an appropriate development language and platform will be selected. Hence, we might feel that an appropriate development language will not be a factor that influences estimate consistency unduly, given that an estimator has experience of the problem domain. However, algorithmic methods usually require calibration to different problem domains. Calibration may be needed because the method was originally designed using data from another type of domain. Furthermore, estimators' estimation consistency within problem domains may be affected for one or more reasons. Intuitively, reasons might include: estimators lack estimation experience in some domains; or the development team(s) may have different levels of experience in different domains, which the estimator finds difficult to take into account. We demonstrate how, in general, the influence of problem domain may be assessed using a Hierarchical Bayesian inference procedure. We also show how values can be derived to account for variations in estimate consistency in problem domains.