Why Can't Developers Estimate Time? • Hacker News Board

Re: Why Can't Developers Estimate Time?

#21

Post by ctdonath » Fri, Apr 08, 2011, 1:50 PM UTC

Lozzer wrote: post #16

I estimate by considering an optimistic, pessimistic and normal value for each task. I then have a spreadsheet that does a modicum of statistical analysis to give you times against probability that the task will be finished. Some of the benefits I find are: 1. Getting into the pessimistic mindset helps produce better estimates 2. Tasks with a large spread are things you aren't really clear about, and are an obvious t…

Need to include "tasks which will take significant time but I can't tell you what they are because we won't know until we get there". Managers can't seem to deal with the notion that 10-30% of a project is completely unknown when writing initial schedules.

Re: Why Can't Developers Estimate Time?

#22

Post by [deleted] » Fri, Apr 08, 2011, 1:53 PM UTC

codelion wrote: post #14

May be because software development is a creative process or the same reason why Artists won't tell you how long they will take to finish a painting or Authors repeatedly miss publisher deadline for books.

[deleted]

Re: Why Can't Developers Estimate Time?

#23

Post by bsaunder » Fri, Apr 08, 2011, 1:53 PM UTC

Almost all bad estimates are due to a lack of information. In software development, the information that tends to be missing are the particulars of the task being estimated (which code needs to be modified, in what way). This missing information is highly unique and not to generally transitive from one programing assignment to the next. Additional information about the process is usually not the problem. Things like CMM tend to focus on the process information rather than the particulars of the coding problem at hand. Which, leads many developers to think: "You're doing it wrong."

Re: Why Can't Developers Estimate Time?

#24

Post by charlief » Fri, Apr 08, 2011, 1:58 PM UTC

Lt. Commander Geordi La Forge: Look, Mr. Scott, I'd love to explain everything to you, but the Captain wants this spectrographic analysis done by 1300 hours.

[La Forge goes back to work; Scotty follows slowly]

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.

Lt. Commander Geordi La Forge: Yeah, well, I told the Captain I'd have this analysis done in an hour.

Scotty: How long will it really take?

Lt. Commander Geordi La Forge: An hour!

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

Lt. Commander Geordi La Forge: Well, of course I did.

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

Re: Why Can't Developers Estimate Time?

#25

Post by k7d » Fri, Apr 08, 2011, 2:00 PM UTC

That's why we were using complexity estimates in points (say 1 to 5) instead of actual time estimates in my last startup. Once you have some worklog, it's easy to calculate how many points the team can get done in a week (or whatever your estimation cycle is). This little abstraction made estimates much more reliable.

I guess some "agile" methodologies propose a similiar approach, but we didn't really follow any specific one, just figured out what works best as we moved along and kept the process as lean as possible.

Re: Why Can't Developers Estimate Time?

#26

Post by hammock » Fri, Apr 08, 2011, 2:01 PM UTC

The author makes the point nicely at the front: "because the nature of the work is creating."

I'm not a developer but I can confidently say that it's not just developers - NO ONE can estimate time when it comes to creative work. I use the term creative loosely, it could be anything from developing a business strategy, to crafting a story, to art directing an original visual, to writing code for a novel problem.

The problem is the same one that makes it difficult to say "when will we have a cure for Parkinson's," "when will we have fusion power," "when will we discover a viable alternative energy"? You often see estimates like 20 years, 40 years, 50 years - but properly interpreted, these aren't actual estimates of the amount of time it will take, but rather like a proxy for a much more probabilistic, uncertainty-oriented notion.

Re: Why Can't Developers Estimate Time?

#27

Post by jospehcanto » Fri, Apr 08, 2011, 2:02 PM UTC

Want to hire the most experienced programmer out of a group of candidates? Ask them to estimate a programming task, then pick the one that gives the longest estimate.

Re: Why Can't Developers Estimate Time?

#28

Post by [deleted] » Fri, Apr 08, 2011, 2:06 PM UTC

btilly wrote: post #11

I prefer to take my advice from someone who has demonstrated the ability to repeatedly run projects and estimate them in advance to surprisingly high accuracy. I therefore recommend Software Estimation by Steve McConnell, available at http://www.amazon.com/Software-Estimation-Demystifying-Pract... .

[deleted]

Re: Why Can't Developers Estimate Time?

#29

Post by hammerdr » Fri, Apr 08, 2011, 2:06 PM UTC

k7d wrote: post #25

That's why we were using complexity estimates in points (say 1 to 5) instead of actual time estimates in my last startup. Once you have some worklog, it's easy to calculate how many points the team can get done in a week (or whatever your estimation cycle is). This little abstraction made estimates much more reliable. I guess some "agile" methodologies propose a similiar approach, but we didn't really follow any spec…

Just to clarify what k7d is saying when he quotes "agile" methodologies:

Any prescriptive agile methodologies (first, do X. then, do Y) are really antithetical to agile. True agile processes are exactly what his own startup did. They used what worked. They implemented a practice (complexity points) that was relevant to their principles (accurate estimation). Of course, you should also be tweaking your process as you go along.

Re: Why Can't Developers Estimate Time?

#30

Post by wladimir » Fri, Apr 08, 2011, 2:08 PM UTC

[deleted] wrote: post #22

codelion wrote: post #14

May be because software development is a creative process or the same reason why Artists won't tell you how long they will take to finish a painting or Authors repeatedly miss publisher deadline for books.

[deleted]

I do agree with him.

In my opinion, software development is exactly a creative process. Many times, you have to come up with a creative solution that fits within certain constraints. Also, in the beginning usually only a vague image is known. The artist (developer) has to fill this in and make sure it is what the client wants.

Also, many creative works are collaborative efforts as well these days. I'm not sure how that changes anything. If anything, it makes estimates harder.