To me the problem of estimation is fairly straightforward. Mike Cohn's work in AEAP is thorough and worthwhile and probably still the best resource for solving

To me the problem of estimation is fairly straightforward. Mike Cohn's work in AEAP is thorough and worthwhile and probably still the best resource for solving the problem of estimation with any regularity. http://www.amazon.com/Agile-Estimating-Planning-Mike-Cohn/dp/0131479415 http://www.amazon.com/Agile-Estimating-Planning-Mike-Cohn/dp... But the simple version of the problem, in my experience, is related to the 80/20 rule. No matter how many times a developer goes through the process of estimation -> development -> slippage, whether on a big scope or small, we will inevitably estimate the very next project as if only the clean 80% exists and the 20% will magically disappear this time. Let's back up. In my experience the 80/20 rule (or Pareto Principle) applied to software estimation means that you will spend 80% of your time writing 20% of your features. Usually this has to do with various technical blocks, edge cases, framework incompatibilities -- the list goes on and varies wildly from one feature or application to the next. You will spend 20% of your time working on 80% of the feature(s). This is the stuff you have done before: basic CRUD, ORM-fu, REST actions -- these are the clean, easily understood software tasks that you see right in front of you as the happy yellow brick road to feature completion. And no matter how many times we wash-rinse-and-repeat this cycle, the next time a PM or colleague asks us "how long this will take," we will stare at that beautiful, pristine part of the path that we understand and know and have done before, and conveniently elide the fact that our development process has never been that clean and there is a nasty 20% (what? my code won't connect to the staging server because of some weird certificate problem? what do you mean my gems are incompatible? I can't get 'make' to build this gcc lib!! IE is doing what?? Why do our servers treat HTTP basic auth in such a non-standard way?) just waiting to jump out, muss your hair, laugh in your face and dance like a hyperactive monkey all over your keyboard.