People are bad estimators. We all know it and still customers ask "when will it be done".
This talk lists a dozen explanations why estimating doesn't work and how potentially we can solve the more global problem of needing them.
11. Vicious Cycle in IT
BUSINESS WANTS
A LOT
WE GIVE
BUSINESS STARTS UNREALISTIC
TO PRESS ESTIMATES
IT WE FAIL TO
BECOMES EVEN
DELIVER
HARDER TO
DELIVER