- Introduction
- B2B E-Commerce Primer
- Overall Function Point Counting and Estimation Methodology
- Benefits of Function Point Counting and Estimation
- Extensions to IFPUG CPM 4.1
- The Function Point Counting and Estimation Repository
- The Function Point Counting and Estimation Team-based Process
- Function Point Estimation Worksheet Example Segment
- Other Applications
- Internal Challenges at eSell
- Summary and Conclusions
- Final Questions to Ponder
This chapter is from the book
This chapter is from the book
This chapter is from the book
Function Point Estimation Worksheet Example Segment
A segment of an actual FPE worksheet (created in Excel) is included in Figure 41-1 as an illustration of the FPE process described. Each line on the worksheet is a functional requirement from the end-user perspective, in the form of an ability-to with all associated size and effort estimates attached.
Column 1: A numeric ID is assigned for reference purposes.
Column 2: The new or customized functionality (ability-to) is articulated by the Specialist.
Columns 3-7: The FP Specialist enters the function point size (estimate) for the EI/EO/EQ/ILF/EIF associated with the new or modified functionality.
Column 8: The worksheet calculates the FP total for that ability-to, indicating the estimated total size of the ability-to (31 FP in this example).
Now project team productivity for this ability-to is estimated.
Column 9: The FP Specialist enters the type of technology and degree of back-end integration used to implement this function. Currently there are three choices (W, C, A) in increasing complexity and thus decreasing productivity.
Column 10: The FP Specialist enters the level of reuse expected to implement this function. Currently there are two choices (R and N) in decreasing reuse and thus decreasing productivity.
Column 11: The FP Specialist enters the overall subjective risk associated with all known (and forecast unknown) factors involved with this function. Currently there are three choices (L, M, H) for increasing risk and thus decreasing productivity.
The worksheet uses these three factors to look up in the historical productivity database what productivity was achieved in the past for work of that profile.
Column 12: The estimated productivity for this individual ability-to is calculated by the worksheet and placed in Column 12. Here it is 33.3 FP/SM for the combination of the three productivity factors chosen (A-R-M).
Columns 13 and 14: The worksheet uses simple arithmetic and computes the estimated effort in staff-months (SM) and staff-days (SD) for Columns 13 and 14, respectively. Here this is 0.9 SM and 20 SD.
Column 15: Finally, the FP Specialist logs all the changes, risk elements, assumptions, notes, reminders, and other miscellaneous information that would be relevant to justify and document the estimate, for the customer to validate or for the design team to use.
When all ability-to items are analyzed, the worksheet calculates (at the bottom) the total function point size estimate (302 FP), the average productivity (24.2 FP/SM), and the total effort from which contractual costs are computed (12.5 SM, 276 SD).