Friday, July 13, 2012

How big is a 1?

Nothing sinks a project faster than a poor estimate, or rather, an estimate that sets the wrong expectation. Part of the problem with setting expectations is finding the right words to paint an idea of the development  effort.

It usually starts to go wrong when somebody tells a prospective client that the team estimates work in story points and 1 point “is about a day”. Wrong!  And too late.
The client will never lose the impression that a point is really just another word for “a developer day” and they will always be suspicious why it’s taking weeks to do what apparently was rated as a few days work.

A point is not always a day. I’m on teams right now that are only getting 1 or 2 points done per week. I was on a project where it took 3 weeks to complete a one point story.  I’ve also been on a project where the stories were so small, we stopped using points completely and did 3 – 5 stories a day.

So how big is a 1 or rather, what should a 1 represent?

All we want is some way to express time and effort relative to everything else that’s on the table.  

A 1 seems like an easy way to say that of all the things there are to do, each story in this pile will likely take about the same effort and time to do and they are all smaller than any other story on the table (or in the list).  From there, 2, 3, and 5 are useful to express increasingly larger scales of work, with anything above 5 or 8 signaling something big enough to require decomposition. 

But although it is convenient to use numbers to express relative positions on a sizing scale; using numbers tempts people to apply the same numbers without adjustment to generally quite unrelated timing scales.

Eliminating the numbers and using other mental images may be better for illuminating story sizing and starting a discussion around the development effort that might be involved. Let’s try some different scales:

     Cherry, apple, cantaloupe, watermelon, holiday fruit basket.
     Skateboard, bicycle, Vespa scooter, Ford Escort, 18-wheeler moving van.
     Pebble, rock, boulder, Corinthian column, Stonehenge.
     Stick horse, pony, racehorse, the Budweiser wagon, a circus carousel.

The next time you are sizing stories (and yes, call it sizing not estimating), it could be interesting to forget about numbers and try using some flashcards with pictures of objects instead. Your team might end up saying, “This week we finished three little ponies." Or, "The last time we did a beer wagon, it took a week and a half."  

1 comment:

  1. Great thoughts you got there, believe I may possibly try just some of it throughout my daily life.

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