Sizing Your Software: A Fast Path Approach

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Learn a fast-approach to sizing your software with the use of function point analysis.

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  • Which of these things are the most important to you or frustrating or challenges…
  • Sizing Your Software: A Fast Path Approach

    1. 1. Sizing Your Software: A Fast Path Approach David Herron David Consulting Groupd.herron@davidconsultinggroup.com
    2. 2. Why Sizing is Important• Requirements – An ability to evaluate the size of the requirements based upon functionality being requested• Estimation – Size is a key variable required to effectively estimate the level of effort• Process Improvement – Requires a consistent sizing measure to be used as the basis for comparing levels of performance• Change Control – A repeatable, consistent size measure is necessary to properly manage client expectations©2012 David Consulting Group 1
    3. 3. Characteristics of an EffectiveSizing Metric• Meaningful to both developer and business user• Defined (industry recognized)• Consistent (methodology)• Easy to learn and apply• Accurate, statistically based• Available when needed (early)©2012 David Consulting Group 2
    4. 4. The Function Point Methodology Five key components are identified based on logical user view• External Inputs• External Outputs External External External Input Inquiry Output• External Inquiries• Internal Logical Files• External Interface Files Internal Logical Files External Interface Application File©2012 David Consulting Group 3
    5. 5. The Function Point Methodology Complexity Components: Low Avg . High Total Internal Logical File (ILF) __ x 7 __ x 10 __ x 15 ___ External Interface File (EIF) __ x 5 __ x 7 __ x 10 ___ External Input (EI) __ x 3 __ x 4 __ x 6 ___ External Output (EO) __ x 4 __ x 5 __ x 7 ___ External Inquiry (EQ) __ x 3 __ x 4 __ x 6 ___ Total Unadjusted FPs ___ Record Element Data Elements (# of unique data fields) Data Types Relationships or Low Low Average File Low Average High Types Referenced Average High High©2012 David Consulting Group 4
    6. 6. The Function Point Methodology Complexity Components: Low Avg . High Total Internal Logical File (ILF) __ x 7 __ x 10 __ x 15 ___ External Interface File (EIF) __ x 5 __ x 7 __ x 10 ___ External Input (EI) __ x 3 __ x 4 __ x 6 ___ External Output (EO) __ x 4 __ x 5 __ x 7 ___ External Inquiry (EQ) __ x 3 __ x 4 __ x 6 ___ Total Unadjusted FPs ___ Record Element Data Elements (# of unique data fields) Data Types Relationships or Low Low Average File Low Average High Types Referenced Average High High©2012 David Consulting Group 5
    7. 7. The Function Point Methodology General System Characteristics Data Communication On-Line Update Distributed Data Processing Complex Processing Performance Objectives Reusability Heavily Used Configuration Conversion & Install Ease Transaction Rate Operational Ease On-Line Data Entry Multiple-Site Use End-User Efficiency Facilitate Change An assessment of the General Systems Characteristics results in a Value Adjustment Factor (VAF) Final Calculation: Total Unadjusted FP X VAF = Final Count©2012 David Consulting Group 6
    8. 8. The Counting Process Identify the Identify the Evaluate the Application Five Functional complexity Boundary Elements Compute an Assess the Compute a Compute a Unadjusted 14 GSCs Value Adj. Final FP FP Count Factor Count©2012 David Consulting Group 7
    9. 9. Common Criticisms of Function Points• FP methodology terms are confusing• Too long to learn, need an expert• Need too much detailed data• Does not reflect the complexity of the application• Takes too much time• We tried it before©2012 David Consulting Group 8
    10. 10. FP Lite Counting Process TM FP Lite requires only 3 steps TM Identify the Identify the Detail Y Evaluate the Application Five Functional Data complexity Boundary Elements Available N Compute an Assess the Compute a Compute a Unadjusted 14 GSCs Value Adj. Final FP FP Count Factor Count©2012 David Consulting Group 9
    11. 11. FP Lite Impact Analysis TM What is the impact on size accuracy when performing a FP count that assumes everything is of average complexity?Use FP Lite when: TM• You don’t have enough detail data to determine the complexity• You don’t have the time to perform a full count• You don’t have the skill (or motivation) to perform a full count©2012 David Consulting Group 10
    12. 12. The StudyThe intent of the study was to determine:• What is the statistical variability between a full count and FP Lite count TM• What is the effort involved for a full count vs. a FP Lite TM countApproach:• Collected data from two separate sources• Counts were performed by experienced function point counters all counting consistently• Counts were randomly selected from a larger group of counts©2012 David Consulting Group 11
    13. 13. Project Profile Data: Group 1 PROFILE 30 Enhancement projects from (30) different applications Size 0 - 50 fps 11 Smallest 3 51-150 fps 10 Largest 1,916 Over 150 fps 9 Average Size 198.47 30 FP Entities Platform EI 37% Client Server 14 EO 20% Web 6 EQ 16% Mainframe 9 ILF 24% PC 1 EIF 3% 100%©2012 David Consulting Group 12
    14. 14. FP Lite Statistics: Group 1 TMAssumption: Statistics based on Adjusted function pointsAll Projects Detail Count 5954 FPs FP LiteTM 5471 FPsVariance* at the Project Level Extreme Median Range Low High Low High All Projects -23.69% 32.16% -8.90% 12.90% 0-50 fps -21.42% 32.16% -8.62% 26.07% 51-150 fps -23.69% 19.72% -10.22% 12.23% Over 150 -22.77% 4.18% -8.91% 3.65% fps *Variance expresses the performance of FP LiteTM relative to the actual count©2012 David Consulting Group 13
    15. 15. Group 1: Range Analysis 40.00% 30.00% 20.00% 10.00% 0.00% 0 100 200 300 400 500-10.00%-20.00%-30.00% Group 1: 47% were less than +/- 10% 74% were less than +/- 20% 26% were greater than +/- 20%©2012 David Consulting Group 14
    16. 16. Distribution Analysis Group 1 10 9 8 Distribution 7 6 5 4 3 2 1 0 30 / 40 20 / 30 10 / 20 0 / 10 0 / -10 -10 / -20 -20 / -30 Variance Range©2012 David Consulting Group 15
    17. 17. Level of EffortQuestion - How much time is saved by using FP Lite ? TMSurveyed 9 CFPS Counters. Data points reflect their notional view of how much time it takes to count various sized projectsResults: Size Effort (hrs.) FPA FPL Productivity <50 2.5 2.0 20.0% 50 - 150 4.3 3.5 18.6% >150 - <300 8.8 5.5 37.6% 300-650 13.9 9.6 30.9% >650 - <1000 20.8 14.3 31.3%©2012 David Consulting Group 16
    18. 18. Initial Observations• With FP LiteTM the variance tends to decrease as the size of the project increases• Size counts under 50 FPs may have a higher variance• Numerous changes to certain elements may have an impact variability• 70 +% of the FP LiteTM estimates were within +/- 20% of actual.• GSCs were not statistically significant relative to the results of the final count• Using the FP LiteTM approach may be more productive©2012 David Consulting Group 17
    19. 19. Requirements Gathering The FP Lite method of sizing can be used early in TM the lifecycle to generate a preliminary size useful in managing the scope of the project Inquiries USER USER WORK LIST OF MOLDS CENTERS Element Value PARTS Output Inquires (2) 8 PLANT MOLDS PARTS LISTING Data Stores Inputs (1) 4 BILL OF MATERIALS USER Outputs (1) 5 ORDER PARTS Data Stores (3) 30 Inputs PLANT INFORMATION CENTER USER Total Size 47 CHANGE BILL©2012 David Consulting Group 18
    20. 20. Estimating FP Lite can be an effective sizing vehicle to be TM used in early lifecycle estimates DEFINITION CAPABILITY ESTIMATE Schedule PROJECT X PROJECT X RISK REQUIREMENT COMPLEXITY SIZE FACTORS Costs Effort FP Lite©2012 David Consulting Group 19
    21. 21. No Excuse Not to Size• FP Methodology terms are confusing – Simplify the terms, easy to understand• Too long to learn, need an expert• Need too much detail data• Does not reflect the complexity of the application• Takes too much time – Use FP Lite !! TM• “We tried it before” – Well, try it again!!©2012 David Consulting Group 20
    22. 22. Contact UsEmail: d.herron@davidconsultinggroup.comPhone: 1-610-644-2856, ext 21http://www.davidconsultinggroup.com @DavidConsultGrp /DavidConsultGrp /company/David-Consulting-Group©2012 David Consulting Group 21

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