How do you estimate the project effort/schedule of your projects?

Question

Possible Duplicates:
How to create an accurate hour estimate?
Dealing with awful estimates

There are many estimation techniques. From formal ones like Cocomo and Function Points, less formal ones like Story/Feature points, to even less formal like "Toss some dice".

Which method you find most useful or most effective? Why?

What do you do if the estimation method gives results that are not quite exactly what project managers, marketeers or pointy haired bosses expect?

Answer 1

If you use something like FogBugz, it has Evidence Based Scheduling. Apparently it can be accurate down to the day.