This is a humourous demonstration of the planning fallacy (http://en.wikipedia.org/wiki/Planning_fallacy http://en.wikipedia.org/wiki/Planning_fallacy), which i

This is a humourous demonstration of the planning fallacy (http://en.wikipedia.org/wiki/Planning_fallacy http://en.wikipedia.org/wiki/Planning_fallacy), which is a direct derivation of the the anchoring bias (http://en.wikipedia.org/wiki/Anchoring http://en.wikipedia.org/wiki/Anchoring). This bias causes humans to be unable to adjust conjunctive (multiplicative) probability sets down low enough to accurately predict the total time to completion of complex tasks. Basically - even though the actual chance of implementing any part of a program is very high - the multiplied probabilities of all the parts working together fall geometrically towards 0. Due to anchoring, humans don't adjust down far enough which in turns leads them to underestimate the total time to completion of various tasks.