Sins of Estimation

2094 Words9 Pages
10 Deadly Sins of Software Estimation Steve McConnell © 2002 Construx Software Builders, Inc. All Rights Reserved. www.construx.com D e l e ring Softw are P e ct Succe ss iv roj Construx ® Background Estimation Book v Construx Estimate™ v Construx’ Training s v Construx’ Consulting s v www.construx.com 2 consulting u training u software projects u construx.com Art and Science of Software Estimation Science of estimation is well-developed and well-supported by software tools v Art of estimation relies on rules of thumb and still needs some work v 3 consulting u training u software projects u construx.com Almost-Deadly Sins of Software Estimation Sins #20-#11 Sin #20 Estimating how long “it”…show more content…
are developers tend to be introverts and relatively young v Marketing and sales personnel tend to be more extroverted and organizationally senior to the developers they negotiate with v 21 consulting u training u software projects u construx.com Sin #3 Committing to Estimates Too Early in the Cone of Uncertainty The Cone of Uncertainty Project cost (effort and size) 4x Project schedule Most estimates are created here 2x 1.5x 1.25x 1.0x 0.8x 0.67x 0.5x Good estimates aren’ t possible until here 1.6x 1.25x 1.15x 1.1x 1.0x 0.9x 0.85x 0.8x 0.25x 0.6x Time 23 consulting u training u software projects u construx.com Plan to Revise Estimates Throughout the Project Project cost (effort and size) 4x Project schedule 1.6x 2x 1.5x 1.25x 1.0x 0.8x 0.67x 0.5x 1.25x 1.15x 1.1x 1.0x 0.9x 0.85x 0.8x 0.25x 0.6x Suitable only as estimates Suitable as estimates Time and commitments 24 consulting u training u software projects u construx.com Sin #4 Assuming Underestimation has No Impact on Project Results Effect of Estimation Accuracy Non-linear impact due to planning errors, upstream defects, high-risk practices Cost Effort Schedule Linear impact due to Parkinson’ Law s Underestimation Overestimation < 100% 100% >100% Target as a Percentage of Nominal Estimate 26 consulting u training u software projects u construx.com Sin #5 Estimating in the “Impossible Zone” Puzzle Suppose
Open Document