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

michaelrwolfe.com

71–80 of 173 posts

Re: Why are software development estimates regularly off by a factor of 2-3?

#71
post #34

I love this post; it conveys the feel of the experience so well. One of my big aha moments about estimation was a bit in McConnell's Rapid Development . He pointed out that most estimates get made with executives pressuring for short numbers. When you iterate a few times with that, you end up with the smallest number that developers can't absolutely prove is impossible. If you draw out a bell curve of probable comple…

I wholly agree with this, and feel that all project plans should be constructed to mitigate the very high risk of initial estimates. Too many project processes treat estimates as commitments with no backup plan when they (inevitably) go awry. I think a better approach would be to design your system around the idea that all estimates are suspect until proven otherwise, which of course leads to iterative approaches etc…

Your point about estimate risk is excellent.

I agree you can't run a business without any idea when anything will ship. But to get a good idea when things will ship, you don't need estimates.

For example, in the Lean world there's something I've heard called "Disneyland scheduling". You break the project down into lumps. You maintain a queue of the lumps. You measure the average time from position X in the queue to being released.

Now you have a reasonable early warning system for when things will ship. Which is generally much better than what people have with most projects, which is a fantasy date.

Re: Why are software development estimates regularly off by a factor of 2-3?

#72
post #18

So the article tries to describe the hidden complexity of software with a hiking analogy but then it leaves a huge part missing. Let's extend the analogy somewhat... this isn't your first hiking trip. In fact, you've been on dozens and dozens of hiking trips. You're an experienced hiker. Yet, why do you continue to give meaningless as-the-crow-flies estimates of how long it will take you to get to your destination? T…

Been going at it for a couple years now with consulting and freelancing. I've finally gotten good at hitting my estimates. What worked for me was to keep strict time of everything (shoutout to toggl.com, love it!), so I could learn from my mistakes. The trouble is now though, my competition seems to be underbidding me, but in reality they're providing those ~33% estimates they will never realistically keep, while I'm…

It's common in the fixed-bid world to deliberately underbid and charge exorbitant rates for the inevitable change orders. There's an opportunity to compete there, but maybe not an easy one.

Re: Why are software development estimates regularly off by a factor of 2-3?

#73
I really love this article.

In practice a good strategy for companies is reduce unknown to a minimum, the Steve Jobs strategy, just focusing on very few products, with each having the less complexity possible(simplify and simplify).

Only focusing on very few products you could make perfection possible, estimates will be off, they always are when there is unknown, but at least completion will be finite (you will complete it!, which is number one issue with research work for example).

Sounds simple, but is really hard, leaving creative people on their own is dangerous for this reason, they could start new projects, not finishing anything.

Re: Why are software development estimates regularly off by a factor of 2-3?

#74

This post was originally an answer on Quora to the question posed in the title [1]. The question has so far received 222 answers - some of them arguably better, though not as popular as this one. [1] http://www.quora.com/Engineering-Management/Why-are-software...

This blog article is more popular than the quora post because this blog article doesn't require people to sign up to read it.

Re: Why are software development estimates regularly off by a factor of 2-3?

#75
post #18

So the article tries to describe the hidden complexity of software with a hiking analogy but then it leaves a huge part missing. Let's extend the analogy somewhat... this isn't your first hiking trip. In fact, you've been on dozens and dozens of hiking trips. You're an experienced hiker. Yet, why do you continue to give meaningless as-the-crow-flies estimates of how long it will take you to get to your destination? T…

What are you doing now?

Re: Why are software development estimates regularly off by a factor of 2-3?

#76
post #62

The single biggest mistake in the example is giving an estimate for the whole project without knowing team velocity. He tried to plan everything up-front and committed to a completion date, strongly setting delivery expectations. An Agile approach to this walk would have managed the expected target date much better and improved team morale by not overstretching each day ("sprint"). Lots of people think they know (and…

The single biggest mistake in the example is giving an estimate for the whole project without knowing team velocity. I'm inclined to agree. Often though a client will want an estimate (to a ridiculous accuracy) before agreeing to the work. Unless you churn out web page templates or something equally repetitive it's hard to have that relevant velocity. I still come up against client managers that don't "believe" in Ag…

Oh we still get regular "lively discussions" about exactly what features are going to be in a product with a release date 6 months away. I can completely understand though; it's very difficult to leave a conversation being told "we don't know yet, it's likely to be X & Y (but we're not 100% sure) and possibly Z too".
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