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Accurate Estimates - the ultimate oxymoron?

In a two part post on his blog, Amit Rathore discusses the concept of an extreme lean approach - the art of estimating and the value it has in the software development process, by looking at the real impact that time based task estimates have on the software produced. Following a fictitious Web 2.0 start up and assuming quality is non negotiable, some key points are raised:

  • What value is gained by translating the gut feelings of experts into hard estimates?
  • Traditional planning assumes a small number of variables, whereas the reality (like the weather) is much more complex;
  • Questions the value of applying time based estimates  - based on the fact that time spent estimating adds no value to either the customer or the software.

The thing to note, also, is that if we’d spent the time to do detailed estimation (at the task level for each story in the sprint) – we’d have lost another half-day to a day every iteration, and we’d still have no real change in the outcome. Sure we’d have data as to how accurate (or entirely off) our development team was with their estimates, but that would be about it… it wouldn’t change the amount of time they’d have taken. And we’d be short about 5 to 10 percent of the time to actually build the software. Oh boy, we sure made a good decision of not going even slower!

Amit goes on to propose simply using the velocity as a measure of when the project is going to deliver - drawing the parallels of one Redmond based software manufacturer....

After all, what software team ever announced a date that they actually met? These days, many companies just stick the number of the year at the end of the name of their product - Office 2007, Windows 2003, Pocket PC 2006. They’ve given up the charade - they’re now saying they’ll just deliver it sometime in the year.

In summary, given the lean approach and the agile's focus on quality and value delivery the author raises some valid points on the value that time based task-level estimating brings to the party and questions whether they should be invited at all.

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