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Chris Breisch   .NET Data Practices
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There's a very good series at Tyner Blain on Software Estimation With Use Case Points.

The series consists of:

  1. Introduction to software cost estimation
  2. Technical Factors of the Implementation. Primarily non-functional requirements of the system.
  3. Environmental Factors. Mostly characterizing the implementation team, but touching on process as well.
  4. Use Case Quantity and Complexity. The number of use cases and the number of steps within the use cases.
  5. Actor Quantity and Complexity. The number and type of actors and interface.
  6. Effort Estimation. The previously collected data is converted into man-hours.
  7. Free Excel Spreadsheet for Calculating UCP. Download it today. Its free.

There's a lot of good stuff here. The advantage of using UCP for estimation is that we can do it earlier in the process than just about any other method of doing estimation.  The disadvantage is that the results aren't really provable, and may have a high degree of error.

But, remember, one of the tenets of estimation is to continually revisit your estimates and correct them.  The idea is that earlier on you'll have the highest degree of error, and they will continually improve as you go on. Since UCP estimates are done earliest, they're pretty much guaranteed to have the highest degree of error.

So, why even bother?  Because the client (or your boss) wants an estimate as soon as you can possibly give him/her one.  UCP is the only way you're likely to get remotely reliable answers.

Or, as the summary to the introduction puts it:

The earlier in the cycle you can develop reliable cost estimates for software, the greater the chance that you will achieve software product success.

And the spreadsheet is pretty cool, too!  :-)

Posted on Wednesday, April 11, 2007 12:22 PM Architecture | Back to top

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