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Comment by aharrison | Hacker News Reader

I believe that it is erroneous to believe that this has anything to do with software. Estimates in most or all fields are off because humans are bad at predicting timelines. This is referred to as the planning fallacy: http://en.wikipedia.org/wiki/Planning_fallacy

I heartily recommend reading the studies associated with the Wikipedia page, as they demonstrate that this applies to more fields than just software. I will agree that the data does appear to support the hypothesis that the less repetitive the task, the more likely it is to fall subject to the planning fallacy.

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That's appealing, but I'm not sure it is correct. My father spent his career designing power plants. His company had an estimation group tasked with estimating costs and schedules before they ever bid on a job. We're talking projects that could easily run over a decade and cost hundreds of millions of dollars. They did an internal study to see how well the estimators did compared to reality. When management didn't lean on them to shave down an estimate, they were really amazingly accurate.

Now, we're talking about a dedicated group of people who aren't going to do the work themselves and who do nothing but estimation, but still....

But the power plant was not of a different kind each time. Software is missing the sort of standardisation and components that made that doable. Why not is another question....

That doesn't change the point though, does it? Obviously, not everyone has a tendency to underestimate how long it will take to complete a task, depending on both the person and the task. In fact, if an estimation group routinely did this, we wouldn't call them estimation groups (at least I wouldn't).

I'm not sure I get what your point is? Sounds like they did a good job estimating but would give in to pressure to arbitrarily change their estimates? How does that conflict with aharrison's point that estimates/plans are poor in most fields largely because of the way we plan?

Daniel Kahneman talks about the planning fallacy as well as many other biases and faulty heuristics we use when making decisions and predictions in "Thinking Fast and Slow" http://www.amazon.com/Thinking-Fast-Slow-Daniel-Kahneman/dp/...

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