Here’s a great blog about estimates. The first thing I liked about it was the author managed to quote Lewis Caroll in a blog about software estimation.  You can’t really go wrong if you can quote Lewis Caroll and invoke iconic memories about “Through the Looking Glass”.  The specific quote refers to the word “Estimate” and goes like this - “When I use a word it means just what I choose it to mean – neither more nor less.”

The author posits that maybe before we perform an estimate, and certainly before we consume one – we should remind ourselves exactly what an estimate is and is not.  An estimate is an approximation, a statement of possibility and is based on available data which may be incomplete or wrong.  And more importantly we must remind ourselves that an estimate is inexact, does not constitute a promise and is neither target nor deadline.

The author then referenced a previous blog where he introduced the idea of “Accurate Estimates”.  This of course made me cringe because of its similarity to expressions such as jumbo shrimp and liquid gas.  By its very nature it is an estimate.  It will be wrong except in the case of a very unusual coincidence.  He then tends to vindicate himself for this with his response to the question “Why was the estimate wrong?” with the response (the same that I would give) - “The estimate is not wrong because it was an ESTIMATE!”

The author closes by reminding the reader that this is not just an issue with software development.  Think about the last time you drove to work, embarked on a home improvement project, took your kid to the doctors or went to the grocery store.  Did the time spent meet your expectation?  If not, was the activity accomplished in less time than you actually planned for it?  As humans we have a propensity to plan our activities based on how long we would like them to take rather than what history teaches us. When we estimate or ask others for an estimate, we should all take a moment to think about what an estimate is and baseline our expectations accordingly.