Ron Jeffries on Estimation

Ron Jeffries has an excellent write up on estimation on the Pragmatic Programmer website

On Big Bang rewrites

The C3 project’s purpose was to replace the entire family of Chrysler payroll programs. It didn’t accomplish that. Many years later, the subsequent project to replace the entire family of payroll programs has also not accomplished it. We now realize what should have been done.

We should have replaced the broken bits, one at a time, most valuable first.

The fundamental idea of making a complete list of everything payroll, and clicking through it, was wrong.

On (Gu)es(s)timates

It seems that “they” often want to know how long something is going to take, and how much it will cost. My view is that “they” don’t even know what they want, so we bloody well can’t possibly know how long it will take. However, “they” are often powerful and have the money we need, so we need to answer their question, even though we cannot.

Most of the time, “they” know how many people they’ll give us, and how much time. They do that head-shaking thing until we “estimate” the numbers they have in mind. So we should turn the question around. “How much did you want to spend, and when did you hope to see the product?” Then they tell us, and we decide whether we can do something reasonable within that budget. If we can, we go ahead. If not, we politely decline the business.

On vague product ideas

If no one knows, and no one has an idea, odds are the project is too vague and too big. Run away. However, if for some reason you enjoy leaping off cliffs hoping to generate a plan on the way down, here’s something to try. Chet Hendrickson and I call it the “Five Card Method.”

http://pragprog.com/magazines/2013-02/estimation-is-evil

Happy reading.

Why are software development task estimations regularly off by a factor of 2-3?

Developers are often asked to do something which has never been done before, and tell someone else how long it will take before they even know what actually needs to be done.

A slightly modified quote from a quora answer to the question Why are software development task estimations regularly off by a factor of 2-3?.

http://www.quora.com/Engineering-Management/Why-are-software-development-task-estimations-regularly-off-by-a-factor-of-2-3

The question’s answer wiki is an excellent source of insight and so are a few answers.