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Why Are Projects Always Behind Schedule?

priceonomics.com

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Re: Why Are Projects Always Behind Schedule?

#11

Post by te_platt »

This is a great writeup on a simple bit of math that violates common sense expectations. Consider you need to go on a 100 mile trip and want to average 100 miles per hour. Conditions are bad and for the first 50 miles you only average 50 miles per hour. How fast do you need to go to average 100 mph for the whole trip? Clearly 150 mph, right? Except of course you are too late and would have to go infinitely fast as you need to complete the trip in one hour and have already taken an hour.

From the article: "But while there’s a lower bound to how “under” the median a step can be – a step can’t take negative time – there’s virtually no upper limit to how much over the median time a project can take."

So when one step takes a little longer than expected most people fall into the 150 mph trap and get frustrated when they don't meet the false expectation.

Re: Why Are Projects Always Behind Schedule?

#14

Post by yason »

When I was doing more project work I outright refused to give estimates, explaining that I could come up with a random figure that's so low they won't believe it or so high they won't like it, and in any case the figure would have nothing to do with when the project would be complete.

Instead I offered broad time ranges that would narrow down to more accurate ones as work progressed. The managers who had to report those upwards didn't always like that first but they grew to appreciate how the dynamic worked across the project timeline. In the beginning, they didn't know how long because nobody knew how long. Well, maybe definitely more than a month and definitely no longer than a year, and "it all depends". But every week we knew more and they knew more, and the time margins could be shrunk incrementally as soon as difficult tasks turned out to be not so difficult. So the more progress the better everyone knew how we were doing.

That is one gratifying slide to completion but I do admit it probably doesn't work for every team or company.

Re: Why Are Projects Always Behind Schedule?

#15

Post by FilterSweep »

yason wrote: post #14

When I was doing more project work I outright refused to give estimates, explaining that I could come up with a random figure that's so low they won't believe it or so high they won't like it, and in any case the figure would have nothing to do with when the project would be complete. Instead I offered broad time ranges that would narrow down to more accurate ones as work progressed. The managers who had to report th…

This falls into my line of thinking, I tend to be liberal on my project estimates as well.

Unfortunately some project managers / product GMs, and sometimes worse, technical salespeople, fail to understand what all is involved in building the software, web functionality they've come to expect to "just work".

That being said, I've been surprised at how understanding people can be when you explain to them in thought out manner.

Re: Why Are Projects Always Behind Schedule?

#17

Post by AndrewKemendo »

rwcarlsen wrote: post #6
SixSigma wrote: post #4

Hofstadter's law + Parkinson's Law + Murphy's Law = Delay

Hofstadter's Law is my favorite law of all time: "It always takes longer than you expect, even when you take into account Hofstadter's Law." — Douglas Hofstadter, Gödel, Escher, Bach: An Eternal Golden Braid

This always bugged me cause it means every project estimate should be infinite in length.

Re: Why Are Projects Always Behind Schedule?

#18

Post by mattmcknight »

te_platt wrote: post #11

This is a great writeup on a simple bit of math that violates common sense expectations. Consider you need to go on a 100 mile trip and want to average 100 miles per hour. Conditions are bad and for the first 50 miles you only average 50 miles per hour. How fast do you need to go to average 100 mph for the whole trip? Clearly 150 mph, right? Except of course you are too late and would have to go infinitely fast as yo…

Steve McConnell has this example in sin #5 of his 10 deadly sins of estimation...

http://www.ewh.ieee.org/r5/central_texas/austin_cs/presentat...

Re: Why Are Projects Always Behind Schedule?

#19

Post by mason55 »

nhaehnle wrote: post #9

There is actually a nugget of thought in the article beyond the explanations you always hear (and which make up all the comments in this thread as I'm writing this): Even if you base your project schedules on accurate estimates of the median time required for each step, you will still be behind schedule for most projects. The reason is actually quite simple: when things go well, they can only go so well, but when the…

Projects timelines are like naked shorts in the stock market. You have a capped upside but unlimited downside - things can never be done faster than instantly but they can take literally forever (i.e. just never get finished).

Re: Why Are Projects Always Behind Schedule?

#20

Post by analog31 »

AndrewKemendo wrote: post #17
rwcarlsen wrote: post #6

Earlier quoted context omitted.

Hofstadter's Law is my favorite law of all time: "It always takes longer than you expect, even when you take into account Hofstadter's Law." — Douglas Hofstadter, Gödel, Escher, Bach: An Eternal Golden Braid

This always bugged me cause it means every project estimate should be infinite in length.

Zeno's Paradox. The solution is that a series can converge.
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