Estimating "How Long will it Really Take"

First off, I want to say I love Star Trek, especially The Next Generation, and still consider it one of my all time favorite shows. Here is a great scene from Captain Montgomery Scott (James Doohan) and Lieutenant Commander Geordi La Forge (LeVar Burton). Season 6, Espisode 4 "Relics"

Scotty: "Do you mind a little advice? Starfleet captains are like children, they want everything right now, and they want it their way. But the secret is to give them only what they need, not what they want."

La Forge: "Yeah, well I told the captain I would have this analysis done in an hour."

Scotty: "How long will it really take?"

La Forge: "An hour."

Scotty: "Oh, you didn't tell him how long it would REALLY take did you?"

La Forge: "Of course I did."

Scotty: "Oh laddy, you've got a lot to learn if you want people to think of you as a miracle worker..."

So, you have a task to do. How long does it take? The boss wants it done ASAP, you of course want to deliver it with the right estimate.

How best to estimate how long it will REALLY take?

Is it like anything that you have done before?
Do you have to learn anything?
How many unknowns in the specification?
How big is the scope of the project?
How many people have to interact with finishing the task?
How complex is the task?
What dependencies (if any) do you have for finishing the task?
How many other tasks do you have to handle simultaneously?
Is it something new, or something you have to build on?

All of these questions are important to run through your head (as well as others I've missed) and you should be realistic with your expectations. This isn't to say you should pad your estimates to give yourself a lot more time, but instead understand that giving accurate estimates can effect the direction that the project manager will take and will likely affect the direction of other tasks (and dependencies) based on your estimates.

One of the things that is worthwhile, is to document your estimates on everything you work on (both professional and at home) and keep track of how close you are to your estimates. The only real way of getting good at estimating is to do a lot of them.

Scotty also has important advice, that it is more important to deliver within the time you have given than it is to be constantly late.

It is important to give accurate estimates, but unless you are Geordi La Forge, you will likely make mistakes on your estimates. Once you have given your word on an estimate, you are responsible. Often this can have a cascading effect, where promises can be made on delivery dates that are now based on your estimate. Be careful with your estimates, it is better to deliver ahead of schedule than behind it, although right on schedule is obviously the best. Research your estimates always, and sometimes they will shift the course of the project.

From another episode "The Ensigns of Command" Season 3, Episode 2:

Riker: Gentlemen, we're giving you an assignment. The one thing we don't want to hear is that it's impossible.
Picard: I need the transporters to function, despite the hyperonic radiation.
La Forge: Yeah, but that's imp... Yes, sir.

Wesley Crusher: He wants the impossible!
La Forge: That's the short definition of 'captain'.

La Forge: Captain - we can do it. We can modify the transporters.
Picard: Excellent.
La Forge: It'll take fifteen years and a research team of a hundred...
Picard: Mr. La Forge... I believe we will postpone.

It would be really great if all my blog posts were related to TNG episodes :P

Engage,
Michael Hubbard
http://michaelhubbard.ca