The Measurement Practices Committee is very pleased to announce the release of this new Guideline, available for free download from
The Guideline describes three different methods for converting sizes of software items measured by either the IFPUG, Nesma or MkII FP methods to COSMIC sizes.
1.       ‘Total size’ conversion which involves re-measuring a sample of software items using the COSMIC method and seeking a statistical correlation between the first generation and COSMIC sizes. The best-fit correlation formula is then used to convert the sizes of the remainder of the portfolio of software items.
2.       ‘Direct’ conversion, that is re-measuring all items using the COSMIC method but aided by knowledge of the first generation size
3.       ‘Component size’ conversion, i.e. conversion of sizes by establishing average relationships between the size contributions of the components of the first generation sizes and the components of COSMIC sizes (as opposed to establishing relationships at the total size level).
The Guideline explains how to select which method to use depending on the desired accuracy of the converted sizes, the availability of size data at the total or component levels, and the effort available for the conversion exercise.
The Guideline begins with a comprehensive account of the differences between the four methods that must be considered before starting a conversion exercise. The conversion processes are then described in detail and results presented from previous conversion studies. These are used to illustrate the statistical tests and checks that should be used to obtain the most accurate converted sizes.