Thumb Rules in FP sizing

Thumb Rules in FP sizing

The following Rules of Thumb offer ways of approximating the efforts, schedule, defects and some other important metrics using FP sizing method.

References - Seminars by Caper Jones and B Boehm

 

1. Unadjusted FP size of a software = 35 * Number of Logical Files (30-35% variation)
2. Use case points/ 1.25 would give us an approximate FP size
3. FP^1.15 ~ Number of page counts for paper documents associated with a software
4. FP^1.2 ~ Number of test cases
5. FP^1.25 ~ Defect potential for new software project
6. FP^ 0.4 ~ Development schedule in calendar months
7. FP/ 150 ~ Number of personnel required for development of the application
8. FP/750 ~ Number of personnel required for maintenance of the application


Apart from this, there are FP to LOC and vice versa conversions mentioned by both Caper Jones and B Boehm.
Example -
1 FP = 320 statements of basic assembly language
1 FP = 128 statements of C
1 FP = 107 statements of COBOL
1 FP = 53 statements of C++ and so on.

Use these conversion factors for deriving FP from LOC size alternatively you can first derive FP and then translate it into LOC to calculate other metrics based on LOC size. Most of the parametric tool use this method to estimate efforts, cost and schedule.