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Comment by mellavora | Hacker News Reader

Reading a book where Tom Sheppard (former RAF pilot, solo desert adventurer) breaks down the fuel estimation process as:

mpg * terrain factor * safety factor

it's pretty important to him to get his estimates right, so he is rather serious about this.

Assuming your 'gut feeling' is pretty accurate (I suspect it is), you could probably break it down into:

- these components will take X days,

- getting them to work together is an extra Y,

- contingency factor is Z

I honestly don't understand how your gut feeling could be accurate unless you had a well developed sense of those factors, or some similar breakdown of what it takes to deliver a project and where the complexities/unknowns are.

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It's like any other skill you develop from watching something carefully enough times, long enough. I can tell if an edge in a graphic is off by one, two or three pixels without needing to measure it. Mechanics can look at a screw and know what size wrench, and whether it's metric or imperial. Estimating times and prices does involve juggling a lot of variables and potential for overrun or mission creep... but it's certainly not just true in the code world. The design world is worse because the deliverables are so much harder to nail down. If you play "price is right" enough times you just develop a feel for eyeballing it that tends to be accurate. In the end, the most sophisticated system in the world for estimating a project is a black box AI that's constantly adjusting its parameters and weights, and that's basically what an experienced brain does without breaking it down into steps. You can of course break it into steps, but they're all hypothetical and only you understand how one can be extended and another reduced to meet the same target.

It's like cooking.

Okay... yes, ingredients, preparation, bake time... you have to take each into account. It can be hazy when you're estimating 6 months or 8 months, because you're not sure how it will come together after the first 4. That's true, for something that large.

We humans work by analogy. Experienced people think, probably unconsciously, it is similar as these tasks that took about this time. No breakdown required.

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