14.2 Data You ll Need to Calibrate the Tools

14.2 Data You'll Need to Calibrate the Tools

You don't need a lot of data to calibrate estimation tools to use your historical data. If you have data from one or more completed projects, including

• Effort, in staff months

• Schedule, in elapsed months

• Size, in lines of code

you can calibrate some of the models (including Construx Estimate) to use your historical data instead of industry-average data. Historical data from one project is better than nothing. Historical data from three or more projects is perfectly adequate.

The more expensive tools described in Section 14.4, "Summary of Available Tools," tend to use their large databases of historical-project results to justify their high price tags. But if you have historical data from three of your own projects, the estimate you create using your own data will usually be more accurate than an estimate created on the basis of a tool's generic data. Some of the more expensive tools are worth the money, but not for their large historical databases.