Statistics for profit

Joel Spolsky's Evidence Based Scheduling is a smart idea. Really smart.

I have a few questions about it I'd love to have answered, but there's no comments section or forums entry for this post:

• Do you make normal assumptions for the error on estimates? Seems more likely that you would expect the distribution of incorrect estimates to skew towards too long?


• Aren't the errors heteroscedatic, I'd expect the error to be larger on larger bites of data (and likewise, shorter on smaller bites)?


• Can you produce a conditional distribution for the likely finish dates rather than just a confidence interval on the expected on?


• Can you track dependencies in teh schedule, that is can we propogate an uncertainty from one milestone on one developer into the start of another milestone for a second developer, this would really help measure the interaction costs of a large team, which seems to be missing in this model?


• Why is this technology stuck inside of FogBugs rather than being its own product. There are tons of use cases for this in all sorts of knowledge labor fields, why not enable those? Also isn't in an orthogonal feature set to defect tracking?

I don't need these features, but having them would really make me happy.