Estimating

[Jim Bassett]

Anyone know of any good tools, books, whitepapers, etc. that deal with estimating of software development?

[lord loh]

Do you mean the market growth....or the software development life cycle...

There is a UML that deals with something of life cycles...or may be a to do list can be used to calculate % of development...

[Jim Bassett]

I mean software development life cycle.

[proxima centaur]

Bottom line is: you can't give accurate estimates.
This should not come as a shock to your manager.

I think the most accurate I've come when it comes to giving estimates is to use past experience and try to find similar projects or situations.

Otherwise, what I do is I divide the work in very small tasks and I do my best at estimating how long it will take for each little task, never estimating lower than 0.5 days for each item. Then, multiply your estimate numbers by 3 (x3) to take into account various perturbation and problems that could occur. During the course of development, if a new task occurs that you had not previously taken into account, revise the estimate and change objectives if necessary.

If you are about to bust an estimate, re-estimate how long it will take... etc.

The important thing in software engineering is to CONSTANTLY iterate back and modify our "assertions".

This works remarkably well. Less stress for everybody that way.

As for management and project follow-up tools, I use Gantt graphs in Microsoft Project. There are other options as well.

[lord loh]

I have never done a project on a professional scale....only at my leasure...stilll I know that it really never goes as expected. But taking 3 times more time ????? Shocking!!!!!

What is gantt graph? Where can I get a copy of it ?

[Jim Bassett]

Take a look at Microsoft Project for the way they use a Gantt Chart

[proxima centaur]

Originally posted by lord loh
I have never done a project on a professional scale....only at my leasure...stilll I know that it really never goes as expected. But taking 3 times more time ????? Shocking!!!!!

What is gantt graph? Where can I get a copy of it ?

x3 is a "commonly acknowledged" factor for new development projects as programmers tend to underestimate the time necessary to complete a task (or overestimate their abilities ;) ).

However, please note this is an estimate. Sometimes, you can indeed finish a task in 3 times less time than estimated, however, sometimes it just takes longer... Look at it as if it was a "buffer". This is just a method software designers use to be sure to have enough time to finish a project.

However, I have seen projects where the factor has been more in the range of x10. This is not uncommon when adding features for badly designed spagehtti code software. Sometimes, when you dig in the dirt, you find all sorts of skeletons.

So you choose, either everybody is bad at giving estimates, OR it is virtually impossible to be accurate in estimating software cost.

I choose the latter.

Estimating cost is something you have to learn by trial and error, I'm afraid.

For Gantt chart examples, check http://www.smartdraw.com/resources/examples/business/gantt.htm

Microsoft Project is only one of many programs that use Gantt charts.

[Linenoise]

Programmers (at least, me..) also tend to forget interruptions - it may take you a week to code something, but that's assuming 8 hours a day working. If you've got 1-2 hours of meetings a day, and people stopping by/calling with questions, then you're down to 4-5 hours of productive work a day (if you're lucky). This doesn't even consider the Crisis-of-the-Day (requiring all other work to stop), vacation, requirements changes, and simply unforeseen issues.