I’be been meaning to repy to Anthony’s comment on estimation. I said that you need to estimate the tasks and add them up to come up with an estimate with a story. Anthony suggests that that “yesterday’s weather” is a better tool for estimation.

Correctives (“yesterday’s weather” \ load factors) are something that you apply to an estimate, and yes they are good tools. You need to come up with an estimate to correct in the first place, and adding up tasks works for me. It has the benefit of helping to track progress while working on the story.

“When do you think you’ll be finished?”

“Well I have 4 hours estimated left, but it has taken me six hours to get through the previous four……”