Three-point estimates

Question

I am aware of many project estimation techniques, such as top down, bottom up, and analogous estimating. I'm not quite familiar with three-point estimates, how does this type of estimation work? What are the "three points"?

Answer 1

The three points are generally your most pessimistic, most optimistic, and most likely estimates (worst case, best case, somewhere in the middle).  You can take the average of these to derive a single number.  Or alternatively, if you weight the most likely four times and divide by 6, you have the PERT (Program Evaluation Review Technique) estimate basis.