I’m working on a project with many unknowns like moving the app from one platform to another.
My original estimations are way off and there is no way I can really know for sure when this will end.
How can i deal with the inability to estimate such a project. It’s not that I’m adding a button to a screen or designing a web site, or creating and app or even fixing bugs. These are not methods with bugs, these are assumptions made in the overall code, which are not correct anymore and are found step by step and each analyzed and mitigated with many more unknowns.
I happened to write a master thesis about software-estimation and there are lessons I’ve learned:
-1st Count, 2nd compute, 3rd judge – this means: first try to identify items in your work which are countable e.g files, classes, LOCs, UIs, etc. Then calculate using this data the effort (in person/days). Use judgement as the last ressort.
-Document your estimation! Show numbers. This minimizes your risk, thus you will present results not as your opinion, but as more or less objective figures. (In general, the more paper the cleaner the backside)
-Estimation is not a commitment. Commitment is one number, estimation is always a range – so give your estimation as a range ( use cone of uncertainty to select the range properly http://www.construx.com/Page.aspx?hid=1648 )
-Devide: Use WBS, devide your work in small pieces and estimate them separately. The granulity depents on the entire length, but at most a working-package soultn’t be bigger than 10% of entire effort.
-Estimate effort first, then schedule, then costs.
-Consider estimation as support for planing, reestimate on each project phase (s. cone of uncertainty).
I would suggest the book http://www.stevemcconnell.com/est.htm which deals all these points, in particular how to deal with bosses, who try to pull a commitment from you.
Regards,
Valentin Heinitz