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Joining Effort and Duration in a Probabilistic Method for Predicting Software Cost and Schedule

Risk Track




This paper describes a data-driven method for estimating the cost and schedule of software development projects. This method correlates the estimates of cost and schedule such that constraining (perhaps reducing) the cost will impact the estimated schedule and constraining (perhaps compressing) the schedule will impact the estimated cost. This method provides these estimates of cost and schedule that are probabilistic (i.e., provide a range of possible outcomes with associated probabilities of attainment); a capability that is essential to analyzing the impact that affordability and budget constraints have on program cost and schedule and their associated risks. This method incorporates a software development Cost and Duration Estimating Relationship (CDER) system of equations that can be easily calibrated to any historical data set that includes the size, effort, and duration of several completed projects.

The paper includes a practical example of developing a software development CDER from an example data set and then implementing the resulting model to examine several Joint Confidence Level (JCL) and conditional probability scenarios.


Michael A. Ross
r2Estimating, LLC
Michael A. Ross has over 35 years of experience in software engineering as a developer, manager, process expert, consultant, instructor, and award-winning international speaker. Mr. Ross is currently President and CEO of r2Estimating, LLC (makers of the r2Estimator software estimating tool) and is employed as a Technical Expert by Tecolote Research, Inc. Mr. Rosss recent previous experience includes three years as Chief Scientist of Galorath Inc. (makers of the SEER suite of estimation tools) and seven years with Quantitative Software Management, Inc. (makers of the SLIM suite of software estimating tools) where he was a senior consultant and Vice President of Education Services. His prior experience includes 17 years with Honeywell Air Transport Systems (formerly Sperry Flight Systems) and two years with BAE Systems (formerly Tracor Aerospace) during which time he developed and/or managed the development of real-time embedded software for various military and commercial avionics systems. Mr. Ross is a Life Member of ISPA, is currently on the Board of Directors of its Southern California chapter, and regularly presents papers at ISPA/SCEA annual conferences (four of which have been recognized with Best Paper Awards). Mr. Ross did his undergraduate work at the United States Air Force Academy and Arizona State University, receiving a Bachelor of Science in Computer Engineering from ASU.