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Uncommon Sense (for Software)

This blog has been moved to www.UncommonSenseForSoftware.com.

Monday, October 17, 2005

Managing Distraction

Just a quickie today. In software land, people get pulled off their primary projects regularly. Happens all the time. What's interesting, is that even though experienced project managers know this and pad for it to some degree, even they can still drastically underestimate just how often people get pulled.

I've heard numbers like 20 or 30% being passed around as the rule of thumb for padding a schedule for unforseen difficulties. In my experience, if things only deviate from plan by 20 to 30%, it's a dream project. In reality, Time Estimation Error alone can account for as much as 25% of the entire schedule, not including Distraction Rate (can be another 20%), changing requirements (another 30%), or truly unforseen technical difficulties like wasting an entire day trying to figure out why you can't cast the result of a SQL Server SCOPE_IDENTITY() call to an Integer (because it returns a Variant, which needs to be parsed rather than casted). It's no coincidence that many software projects take cleanly twice as long as expected. It's because if you add up the impacts of the top 3 software project killer factors, it's near 100% of the original schedule.

Here's one you should track if you're not already: Distraction Rates. Just keep a spreadsheet of each time someone on the team gets pulled off the project to go do some other work, not related to the project. I'm not talking about counting half-hours. You can even just do a proxy estimation at the end of each week. By the time 2 months has passed, you should see a pretty good chunk of time that's slipped away. If you've kept your spreadsheet up to date, you should be able to calculate on average, what % of each person's time is spent doing work not related to the project, and also for the team as a whole.

Now that you've got the Distraction Rate for each person, you can take the remaining portion of the project (say, another 5 months), and multiply the remaining duration by the Distraction Rate. So if you've got 5 months to go, and your team's distraction rate is 20%, then you're going to be 1 month late due to distractions, if you haven't already included an extra month in the schedule just to account for this one factor.

This kind of trending let's you know what's going to happen, before it actually does. While on any given day, one individual distraction might seem like an anomaly, if you look over a larger window of time (monthly, for example), these kinds of things typically repeat themselves. If it's not one thing taking you away from the project, it's another.


  • I really enjoy the content of your blog, but the overuse of bold makes it very difficult for me to read.

    By Blogger Sean, at October 18, 2005 11:55 PM  

  • Thanks for the comment. You're not the first to mention the use of Bold. Here I was thinking I was being all artistic-like. I'm going to cut that out to make it easier on people's eyes.

    Glad you like the material though.


    By Blogger Craig Fitzpatrick, at October 19, 2005 11:06 AM  

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