Estimating in Agile

I have been reading Software Estimation ( again after a recent conversation with one of the product owners on my team. The Senior engineer on my team has pushed us into a ‘pointless’ estimating process where the estimate is essentially the count of the subtasks in the story. 

The Product owner wanted us to provide time or t-shirt size estimates earlier in the process before we did the work to break up the story into subtasks. This discussion broke down into people arguing over agile… 

Personally, I am quite disillusioned with how we create estimates a part of the Software Development lifecycle. The standard  estimation technique in my experience is to compare a new project with a past project based solely on personal memory and gut feel. Then to double your estimate from what ever you came up with. The computer science and engineering classes I took did not cover anything related to estimating projects. Which is a little strange since assumed the other engineering discipline like Mechanical or Electrical engineering would cover estimates. 

The business executives need estimates so that they can coordinate work, sign deals and generally make money. If you promise a client something and the schedule slips 6 months that is a problem. If you sign a 10 million dollar advertising deal and the delivery schedule slips 3 months its a problem. So the business needs estimates that are accurate to plan things. But if we are just guessing as the engineering team what is the point? If our estimates are constantly wrong and the levels above us ignore them why do we need to waste our time ‘voting’ and playing ‘planning poker’? 

Then there is the issue that in agile we are very loose with stories. Subtasks are added and removed with little oversight. After a story is estimated things can change and suddenly the story goes from 3 subtasks to 10.  The next day 8 of those subtasks are moved into another story. What were we estimating again? 

I will be writing a bunch more on estimation, but some of the things I have gained so far are that expert judgement is considered the weakest means of getting an estimate. The best way is to count something whether stories, square feet of drywall or some other work component. The second means is to use heuristics to compute your way into an estimate. The last resort is expert judgement or gut feel. 

Count > Compute > Judgement

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