Reply To: Software Project Estimation
by
dc_guy
·
about 20 years, 7 months ago
In reply to Software Project Estimation
Cocomo and Function Points are two different kinds of things.
Cocomo is a project estimating methodology. It was developed before Function Points were widely used, so it uses lines of code (LOC) as a measure of software size. LOC is not a very good unit of measurement, for many reasons that you probably already know. In addition, it is very difficult to estimate the number of LOC in a piece of software before it’s written.
Function Points are a unit for measuring the size of software. They measure the quantity of automated functions delivered to the end user, and do not take technology into account. You can count the Function Points in a system before you even decide what platform it will run on, if you have layouts of the screens, reports, and files.
Function Points are recognized as a genuine engineering unit of measurement and were adopted by ISO as a standard in 2002. Measurements in Function Points are far more accurate, consistent, and valid than measurements in LOC.
Function Points are used for project estimating, but they are not an estimating methdology. You must choose an estimating methodology and then use Function Points as the software size measurement as input to the methodology.
Function Points and Cocomo can be used together. However, the Cocomo formulas have never been recreated to use Function Points. The Cocomo software tools convert Function Points into LOC and then feed LOC into their formulas. You end up with an estimate that is just as inaccurate as if you had used LOC to start with.
Therefore, if you want the most accurate estimate, you will probably not use Cocomo because Cocomo does not take advantage of Function Points.
