Software Estimation Demystifying the Black Art by Steve

Software Estimation Demystifying the Black Art by Steve Mc. Connell Presented by Lee Bennett, PMP 1 of 44 Software Estimation Slide 1

Definition of Estimating • De. Marco – [The common definition of an estimate is] “the most optimistic prediction that has a non-zero probability of coming true. ” … the earliest date by which you can’t prove you won’t be finished. • Mc. Connell – … provides a clear enough view of the project to allow … good decisions about how to control the project to hit its targets. Software Estimation Slide 2

Software Estimation • Author: Steve Mc. Connell – Code Complete (1993, 2004) – Rapid Application Development (1996) – Software Project Survival Guide (1998) Software Estimation Slide 3

Cone of Uncertainty Software Estimation Slide 4

Estimating Techniques • • T Shirt sizing Software Estimation tools Wideband Delphi Story Points Software Estimation Slide 5

T Shirt Sizing • Technique – Estimate S/M/L Business Value – Estimate S/M/L Development Cost – Go with the low hanging fruit • Applicability – Very early in project • Results – Doesn’t actually produce an estimate – Eliminates the need to estimate some cases Software Estimation Slide 6

Estimation Tools • Technique – Simulation – Probability analysis – www. construx. com • Applicability – Early to middle for medium to large projects • Results – Can produce highly accurate results* Software Estimation Slide 7

Wideband Delphi • Technique – A structured group estimating technique – Basis of Agiletek’s estimating – Anonymous estimates • Applicability – Early in medium to large projects • Results – 40% improvement over initial group average – Meeting time is expensive Software Estimation Slide 8

Story Points • Technique – Give each story a size estimate from the Fibonacci sequence (1, 2, 3, 5, 8, 13…) – Deliver some stories in an N week iteration – Velocity = [Story Points delivered] / N weeks – Duration = [Total Story Points] / Velocity • Applicability – Early to Middle stage • Example – http: //www. planningpoker. com/ Software Estimation Slide 9

Project Planning and Control Estimating is a skill of project planning. Planning determines appropriate Commitments. Project Controls are needed to help meet Commitments. Software Estimation Slide 10

Questions ? ? ? Software Estimation Slide 11

Estimating Concepts • Use multiple estimating techniques – Estimate by analogy, top down – Estimate by components, bottom up • Estimate size first – Scheduling estimates only after effort estimate is in place Software Estimation Slide 12