Automated Project Cost Estimation : Using Analogies

The ANGEL Project

Introduction

Software Cost Estimation has long proved to be a difficult exercise often resulting in inaccurate and costly errors. Until recently, the bulk of research effort has concentrated on algorithmic models. However the lack of consistent results from algorithmic models has caused researchers to look to alternative techniques, in particular 'machine learning' techniques such as neural-nets and case based reasoning.

One such machine learning approach, estimation by analogy, is the focus of a research project being undertaken by the Empirical Software Engineering Research Group (ESERG) at Bournemouth University. Estimation by analogy involves searching for similarities between a target entity, such as a proposed software project, and a set of historical entities of the same class. Each entity is characterised by a number of attributes that are available at the point when estimates are required. These attributes are used to minimise the Euclidean distance in n dimensional space between a target entity and source entities and thus find the closest 'analogies'. Once a historical analogy has been found, the 'actual' values for the attribute (for example cost) that is to be estimated can form the basis of an estimate for that attribute in the target entity.

Related Publications

The following papers present a more in-depth discussion of the analogy approach in relation to cost estimation:

  1. G. Kadoda, M. Cartwright, and M. J. Shepperd, "Issues on the effective use of CBR technology for software project prediction," presented at Intl. Conf. on Case based Reasoning, Vancouver, 2001.
  2. C. Kirsopp, M. J. Shepperd, and J. Hart, "Search heuristics, case-based reasoning and software project effort prediction," presented at GECCO 2002: Genetic and Evolutionary Computation Conf., New York, 2002.
  3. Mair, C., et al., 'An investigation of machine learning based prediction systems', J. of Systems Software, vol. 53, pp. pp23-29, 2000.
  4. Schofield, C. 'Software Support for Cost Estimation by Analogy', in Proc. 6th European Software Cost Modelling Conference. Rolduc, NL: 1995.
  5. Schofield, C. and M.J. Shepperd. 'New techniques for estimating from function points', in Proc. Annu IFPUG Conf. Scottsdale, Arizona: 1997.
  6. Schofield, C. and M.J. Shepperd. 'Effort Estimation by Analogy: A Case Study' in Proc. 7th European Software Control and Metrics Conference. Wilmslow, UK: 1996.
  7. Shepperd, M.J. and C. Schofield, 'Estimating software project effort using analogies', IEEE Trans. on Softw. Eng., 23(11), pp736-743, 1997.
  8. Shepperd, M.J., C. Schofield, and B.A. Kitchenham. 'Effort estimation using analogy', in Proc. 18th Intl. Conf. on Softw. Eng. Berlin: IEEE Computer Press, 1996.
Related papers by other research groups:

  1. Bisio, R. and F. Malabocchia. 'Cost estimation of software projects through case base reasoning', in Proc. 1st Intl. Conf. on Case-Based Reasoning Research & Development. Springer-Verlag, 1995.
  2. Cowderoy, A.J.C. and J.O. Jenkins. 'Cost estimation by analogy as a good management practice', in Proc. Software Engineering 88. Liverpool: IEE/BCS, 1988.
  3. Mukhopadhyay, T., S.S. Vicinanza, and M.J. Prietula, 'Examining the feasibility of a case-based reasoning model for software effort estimation', MIS Quarterly, 16(June), pp155-71, 1992.
  4. Myers, W., 'Allow plenty of time for large scale software', IEEE Software, 6(4), pp92-99, 1989.
  5. Niessink, F. and H. van Vliet. 'Predicting maintenance effort with function points', in Proc. Intl. Conf. on Softw. Maint. Bari, Italy: IEEE Computer Society, 1997.
  6. Stamelos, I. and L. Angelis, "Managing uncertainty in project portfolio cost estimation," Information & Software Technology, vol. 43, pp. 759-768, 2001.
  7. Stensrud, E. "Alternative approaches to effort prediction of ERP projects," Information & Software Technology, vol. 43, pp. 413-423, 2001.
  8. Stensrud, E. and I. Myrtveit. 'The added value of estimation by analogy: an industrial experiment', in Proc. ESCOM '98. Rome: 1998.
  9. Stensrud, E. and I. Myrtveit. 'Human performance estimating with analogy and regression models: an empirical validation', in Proc. 5th Intl. Metrics Symp. Bethesda, MD: IEEE Computer Society, 1998.
  10. Walkerden, F. and R. Jeffery, 'Software cost estimation: a review of models, process and practice', Advances in Computers, 44, pp59-125, 1997.

Acknowledgements

This research was partly funded by grant (Grant GR/L37298) from the UK Engineering and Physical Sciences Research Council and the Defence Evaluation Research Agency.

Martin Shepperd - 11/7/2002
Email: mshepper@bmth.ac.uk