Estimating ship dates

Joel Spolsky describes a new feature in the FogBugz bug tracking application. Evidence Based Scheduling is an automated way of comparing developer estimates to their past work.

What you get is not just one ship date: you get a confidence distribution curve, showing the probability that you will ship on any given date.

In a nutshell, you figure out how much a developer generally misses their estimates by and then FogBugz uses a random distribution of those numbers to give you a series of possible ship dates along with the probability that the code will ship on those dates.

This is similar to how many software shops already do their estimating, but FogBugz has created a great way of automating it and making it a tool.

Joel includes the detailed mechanics of how FogBugz calculates this, and I’d expect to see other project management tools replicating this in the near future.