Estimating Software Development Effort
with Case-Based Reasoning

G.R. Finnie*, G.E. Wittig* and J-M. Desharnais**

* School of Information Technology
Bond University, Gold Coast
Queensland 4229. Australia
gfinnie@Bond.edu.au
gwittig@Bond.edu.au
** Software Engineering Laboratory in Applied Metrics
7415 rue Beaubien Est, suite 509
Anjou, Quebec, Canada HiM 3RS
(Address Correspondence to Dr. G.R.Finnie)

Abstract
Software project effort estimation is a difficult problem complicated by a variety of
interrelated factors. Current regression-based models have not had much success in
accurately estimating system size. This paper describes a case based reasoning approach to
software estimation which performs somewhat better than regression models based on the
same data and which has some similarity to human expert judgement approaches. An
analysis is performed to determine whether different forms of averaging and adaptation
improve the overall quality of the estimate.

References
Desharnais, J.M., et al. Adjustment Model for Function Points Scope Factors - A
Statistical Study, IFPUG Spring Conference, Florida (1990).
Ferens, D.V. & Gurner, R.B. An Evaluation of Three Function Point Models for
Estimation of Software Effort, IEEE National Aerospace and Electronics
Conference  NAECON92, Vol. 2, 625642, (1992).
Finnie, G.R. & Wittig, G.E. AI Tools for Software Development Effort Estimation,
Proceedings of the Conference on Software Engineering : Education and Practice,
University of Otago, 113-120, (1996).
Finnie, G.R., Wittig, G.E. and Desharnais, J-M. A Comparison of Software Effort
Estimation Techniques: Using Function Points with Neural Networks, Case Based
Reasoning and Regression Models, to appear in Journal of Systems and Software,
1997.
Function Point Counting Practices Manual, Release 4.0 International Function
Point Users Group, Blendonview Office Park, 500828 Pine Creek Drive,
Westerville, OH 430814899, USA, (1994).
Heemstra, F.J. Software Cost Estimation, Information and Software Technology,
vol. 34, no. 10, pp. 627639, 1992.
Jeffery, D.R and Low, G.C. Calibrating Estimation Tools for Software
Development, Software Engineering Journal, 215221, (July 1990).
Jeffery, D.R., Low, G.C. and Barnes, M. A Comparison of Function Point Counting
Techniques, IEEE Transactions on Software Engineering, vol. 19, no. 5, 529532,
(1993).
Kemerer, C.F., An Empirical Validation of Software Cost Estimation Models,
Communications of the ACM, vol. 30, no 5,416-429, (1987).
Kemerer, C.F., Reliability of Function Points Measurement: A Field Experiment,
Communications of the ACM, vol. 36, no 2, 85-97, (1993).
Lootsma, F.A., The Relative Importance of the Criteria in the Multiplicative AHP
and SMART, to appear in European Journal of Operations Research, 1997.
Matson, J.E., Barrett, B.E. and Mellichamp, J.M., Software Development Cost
Estimation Using Function Points, IEEE Transactions on Software Engineering, vol.
20, no. 4, 275287, (1994).
Mukhopadhyay, T., Vicinanza, S.S. and Prietula, M.J., Examining the Feasibility of
a Case-Based Reasoning Model for Software Effort Estimation, MIS Quarterly, vol.
16, no. 2, 15517 1, (1992).
Srinivasan, K. and Fisher, D., Machine Learning Approaches to Estimating Software
Development Effort, IEEE Transactions on Software Engineering, vol. 21, no.
2126-137, (1995).
