Your agile team over-estimates stories? Then check this!
I have passion towards psychology and human behaviour and I find them really interesting. Last week while reading more about agile planning I stumbled upon very interesting experiments done with software people to see the impact of different factors on agile sizing. I find them really interesting and worth sharing.
I believe that sizing and estimation are psychological activities that don't depend only on the facts, but more on our perception of the facts. The atmosphere of our sizing will impact the size. The experiments below might convince you, shock you and some of them will make you laugh out loudly :D
1. The impact of irrelevant information
Dear product owner, as a software engineer I find it hard to ignore irrelevant information.. as human beings we all do have the same issue.
Basically, when you put irrelevant information in your user story, the team will just think that it’s somehow relevant, and will include it in their sizing. Sounds weird? check the experiment
2. The impact of specification length
That's a long document, things don't seem to be easy at all.
I stopped at this finding a LOT. It has nothing to do with the complexity of the requirement or the amount of information in it. It's purely text formatting of the requirement to make it look longer, while it's not.
One page requirement estimated to take 117 hours, spread the same requirement text on 7 pages makes it 173 hours!!
3. The impact of extra requirements
I'll talk to you about this story, but don't include it in your estimates.
I believe the psychological reason for this is that the team will think that excluding this user story means that the other ones are hard, that's why we don't include another related story as part of the scope.
4. The impact of anchoring
It's not always that the first who speaks loses, it depends on the price they set
This one is interesting, It's related to bargaining somehow. You tell the team I believe it's medium effort.. or the customer knows that it's minor.. that's a way of impacting their estimate because you're manipulating their perceptions of the fact. Remember what I said at the beginning?.. It's not about the fact but more of our perception of the fact. The experiment below shows anchoring impact on the estimates
These findings helped me see things from another angle and be sure that it's not only the requirement that might lead to higher/lower estimate but also how I package it and the atmosphere of the planning will impact the story's estimate more than I used to imagine.
Have your own examples?
I'd be happy to know more regarding this topic and in case you met something interesting please don't hesitate about sharing ;)
Footnote: Images below are from a presentation by Mike Cohn regarding agile planning and estimation. This guys is an awesome agile pioneer and I strongly advise you to follow his blog for many interesting things about agile software.
