The Difficulty of Short Term Software Estimation

December 29, 2018

I’m constantly amazed at how bad I am at estimating short-term software effort (I’m better at medium-term estimation, e.g. 1–2 months). If I’m honest, I often underestimate effort by a factor of 3(!) when estimating work that takes 1–10 days.

This is due to the disproportionate effect of interruptions and minor roadblocks on short-term projects. Because the task itself is so small, any impromptu meeting, unplanned chore, or having to work around a tool failure takes up a huge proportion of the feature’s schedule.

These effects are amortized on longer project timelines, but they are devastating to short projects.

Dave’s Uncertainty Principle: the smaller the feature, the more likely your estimate will turn out to be wildly optimistic.