1. Knowledge Exchange Forum October 26, 2004 Estimating Software Project Size from Use Cases Nicholas F. Russo, PMP CACI Technologies, Inc.

2. Nicholas F. Russo, PMPKXF – October 2004 2 Estimating Software Project Size from Use Cases The General PROBLEM: Estimating Software Projects (Size in Source Lines of Code (SLOC) and Effort (Person-Hours)) is difficult at best and often more art than science. The tools/methods that do exist require expert knowledge or experience, often beyond what the assigned Project Manager possesses.

3. Nicholas F. Russo, PMPKXF – October 2004 3 Estimating Software Project Size from Use Cases The specific problem (that I encountered): Came onboard an underway Software Project. The initial software project size was estimated by someone else based on an analysis of a so-called similar project using function point analysis. A new/revised estimate was needed as part of an SEI CMMI Level 3 assessment. It was difficult to impossible to make use of the previous function point analysis.

4. Nicholas F. Russo, PMPKXF – October 2004 4 Estimating Software Project Size from Use Cases How can we solve this problem? What about the Use Cases?: Already completed and well documented. They are real, discrete entities and represent the functional requirements of the to-be-developed software. The references listed at the end of this presentation fully document the basis for using Use Cases.

5. Nicholas F. Russo, PMPKXF – October 2004 5 Estimating Software Project Size from Use Cases Model Description/Formula (The Bottom Line): Categorize all of your Use Cases as follows: 4 – System of Systems 3 – System 2 – Subsystem Group or CSCI-Level 1 – Subsystem or CSC-Level 0 – Class or CSU-Level Apply the following formula (If there are N1 use cases at level 1, N2 at level 2, N3 at level 3, N4 at level 4): Total Size = [(N1/10)*7 + (N2/10)*56 + (N3/10)*448 + (N4/10)*3584] * Total Size is in thousands of Source Lines of Code (kSLOC)

6. Nicholas F. Russo, PMPKXF – October 2004 6 Estimating Software Project Size from Use Cases And now for an example (using an Excel Spreadsheet to calculate the results):

7. Nicholas F. Russo, PMPKXF – October 2004 7 Estimating Software Project Size from Use Cases

8. Nicholas F. Russo, PMPKXF – October 2004 8 Estimating Software Project Size from Use Cases How and when can you make use of Use Cases? For Underway Software Projects: Once the Use Cases are completed, use this methodology to obtain an updated Size and Duration Estimate. For New Software Projects: Look at similar projects and use their Use Cases as basis for estimating your project: with appropriate modifications if known at the time.

9. Nicholas F. Russo, PMPKXF – October 2004 9 Estimating Software Project Size from Use Cases References : 1. Use Case Points - Resource Estimation for Objectory Projects, Gustav Karner, Objective Systems SF AB (copyright owned by Rational Software), 1993 2. Estimation of Effort Based on Uses Cases: John Smith, Rational Software, Whitepaper, 1999

10. Nicholas F. Russo, PMPKXF – October 2004 10 Estimating Software Project Size from Use Cases A Final Thought: “It is better for the project manager to be able to obtain estimates early for planning purposes, and then refine them iteration by iteration, rather than delaying estimation and proceeding in an unplanned fashion.” John Smith, Rational Software

11. Nicholas F. Russo, PMPKXF – October 2004 11 Estimating Software Project Size from Use Cases Q & A: