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Iterations are Bad for Your Health

2008 October 28
by Nayan Hajratwala

Well, not really, but iterations are not as important some of the Agile community makes them out to be, in the way that they are typically thought of.

Short iterations. Long iterations. Who gives a rip? The important thing is that you are regularly tracking your team’s velocity. Take this Big Visible Velocity Chart from my current project:

Ouch! That Velocity Hurts!

Ouch! That Velocity Hurts!

We track velocity weekly (using Ideal Days), only counting up the velocity for stories that are completed before Monday morning. As you can see, we seem to have developed a fairly regular cadence of slow week/fast week/slow week/fast week… So what’s going on here? Do we bring a keg into the team room every other week? Are we really bad at estimating?

Actually, the cause of this sawtooth motion is simply that we tend to not be *quite* done with things in a given week, so a lot of the stories get counted in the following week’s tally. For example, in Week 7, we had two 4 iDay stories and one 2 iDay story allocated. The 2 iDay story was completed by the end of the week, but the the 4 iDay stories didn’t get finished until the following Monday afternoon. Therefore, we counted 2 iDays for week 7, and the remaining 8 were lumped into the week 8 metric.

Now, we could get into a big discussion about how our stories are too big, or that our iterations are too short, but in reality it doesn’t really matter. What matters is that from the data we’ve collected, we can come up with a fairly accurate measure of our teams velocity. (We had a string pulled across the chart that we adjusted each week to indicate the trend line, but the tape wasn’t strong enough to hold it up). We can use that velocity to estimate our team’s capacity and deliverable dates, and have done just that on this project.

By the way, in case you hadn’t noticed, this chart is *proof* that our team’s velocity is “off the charts” :-)

What do you think? Are iterations overrated?