Let Trust YourEstimates Volodymyr Voytyshyn 02/19/2012
Have you ever estimateddevelopment tasks before startwork on them?How accurate were your estimates?What did you do when youunderestimated or overestimatedthe task?Have you ever estimated wholeproject before its start?
The Goal How make estimate of software project efforts BETTER?
Main Points Why Good Estimate is Important? Some Anti-Patterns in Projects Estimation Estimation Approaches Overview PERT in Action
What is an estimate? Estimate is a probability value What is the confidence range? What is the probability that we’ll exceed the estimate?
Estimation Approaches Your own experience in similar projects Expert’s estimation: – PERT, Program / Project Evaluation and Review Technique General techniques based on industry experience: – FPA, Functional Point Analysis – COCOMO, Constructive Cost Model
PERT PERT - Program / Project Evaluation and Review Technique The technique was designed at 1958 during project on the creation of missiles "Polaris" Input data: hierarchical structure of project tasks Output data: probabilistic estimation of efforts
Functional Point Analysis Was designed by Alan Albrecht and first published at 1979 Input data: logical model and requirements for software project Output data: functional points Main benefit: unified and platform independent approach for estimation all projects in company
COCOMOCOCOMO – constructive cost modelWas designed by Barry Bouem and first publishedat 1981Input data: KLOC – thousands of logical codelinesOutput data: effort estimate in man-month
Task Automated ordering system for company which specializing on wholesale trade Customer should be able to create an order Manager should be able process an order Email notification for all steps of order workflow 1C synchronization
ConclusionA. Underestimate has very negative impact on projectB. Software project estimation is not a guessingC. We can use and combine several estimation approaches: – Experience on similar projects – PERT – FPA – COCOMO
Information Sources Software Project Management Lectures http://www.arkhipenkov.ru 10 Deadly Sins of Software Estimation http://construx.com/Page.aspx?cid=2929 Software Estimation: Demystifying the Black Art http://www.microsoft.com/learning/en/us/book.a spx?ID=2425&locale=en-us