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UncleEntity

It’s called The Scotty Principal;

Kirk : How much refit time before we can take her out again?

Scotty : Eight weeks, sir. But ye don’t have eight weeks, so I’ll do it for ye in two.

Kirk : Mr. Scott. Have you always multiplied your repair estimates by a factor of four?

Scotty : Certainly, sir. How else can I keep my reputation as a miracle worker?

Kirk : [over the intercom] Your reputation is secure, Scotty.

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A factor of four is a good rule of thumb for a CTO receiving a time estimate from an engineer.

- How long will the upgrade take ?

- Two weeks at most.

- Ok, talk to you two weeks from now. (CTO proceeds to jot down in his report to the CEO: "Upgrade: 8 weeks").

My thesis advisor said it always takes π times longer to do something than you expect.

The rule of thumb I heard was:

An hour = day

Day = week

Week = month

Month = year…

I've learned that Engineers approximate and use π = 3.

So now we've gotten our time estimate down from 4x to 3x. Talk about efficiency!

3 is the number I have heard many times from different PM's. Engineers tend to interpret a bit 'how long will it take' is 'how long will it take YOU'. So you say 2 weeks. The PM is thinking plus QA, plus rework, plus shipping. That usually is about 3x or ~6 weeks.

But that extra time is the PM's job to add on, not the engineer's. If you ask an engineer "how long will it take," you should expect to get back "here's how long it will take me," not "here's how long it will take me and the other people you manage".

You are exactly correct but that is not what people really ask. It takes awhile for engineers to realize it. By that time they are stressed out and do not know how to manage the PM. The PM is usually not a subject matter expert they manage tasks. They do not even know they need those things. So they fully expect you 'the expert' to know it. Is it 'right' not really, but it is reality and a side effect of how many people become PM's.

Pi is more accurate than 3. I like pi.

π , numerically, is only as accurate as you approximate it to.

3 can be used as an approximate for π.

Hofstader's Law, is that it always takes longer than you expect, even when you take into account Hofstadter's Law.

My friend works at a company where they don't even ask for estimates. The "product management" makes up a schedule, then wonders why they are "late." It's laughable.

For junior engineers - double it an increase by an order of magnitude. 1 day == 2 weeks For senior engineers - double it

A friend back in Cambridge has the rule "Increase unit by one and double the number", so 1 hour becomes 2 days, 3 days becomes 6 weeks, etc.

Seems pessimistic, but given the long tail of should-be-minor bugs in prominent apps, my guess is there's correct.

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