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Project Management

Project Management. Estimating 'Function Point Analysis'. Top Down. Estimating Methods. Analogy using Expert Judgement Historical Data. Other. Bottom Up. Estimating to a Known Price Price to Win Guess. Detailed Work-Breakdown Procedural Methods. Algorithmic Models.

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Project Management

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  1. Project Management Estimating 'Function Point Analysis'

  2. Top Down Estimating Methods Analogy using Expert Judgement Historical Data Other Bottom Up Estimating to a Known Price Price to Win Guess Detailed Work-Breakdown Procedural Methods Algorithmic Models Parameter Driven Cost Models

  3. Background to Function Point Analysis • Top Down Method • Provides a rough estimate of effort and time • Suitable for systems development of Transaction Processing Systems • Useful starting point for understanding estimating and metrics • Government recommended method through CCTA

  4. Method Identify Functions Effort & Duration Complexity Cost Functional Specification ? Risk/Performance Factors Outcome Information Basic Steps + +

  5. Calculate Function Point Count Inputs Outputs Entities Adjust Function Point Count Determine System Complexity Technical Complexity Functional/User Requirements Assess Risk Factors and Constraints Calculate Development Effort Total System Effort Effort by Phase/Stage Adjust work days and elapse times appropriately Productivity Guide-lines FPA Estimates Summary of Estimates

  6. FPA - The Steps • Identify all the transactions • Size each transaction 2b Sum the counts for all transactions 2c System Size=Sum of Weighted Counts 3 Rate system complexity • Calculate adjusted FP count • Determine effort • Determine elapsed time • Apportion effort & elapsed time to stages • Adjustestimates for risks and constraints

  7. Functions triggered by some event that causes data to be input/stored/amended/output E.g. Input Details of ... Display Summary of ... Print Report of .... 1 Identify All the Transactions Identify All Transactions Required by the System

  8. Processes Transaction 2a Size Each Transaction The Number of Input Attributes (I) The Number of Output Attributes (O) The Number of Entities (E)

  9. Transaction 1 I E O 20 5 4 Transaction 2 1 8 20 Transaction 3 5 2 4 I = 33 E = 8 O = 28 2b Sum the counts Sum Inputs, Entities & Outputs for all Transactions

  10. I E O 2b Sum the counts Transaction 1-11 200 50 40 Transaction 12-29 10 80 200 Sum Inputs, Entities & Outputs for all Transactions Transaction 30-38 50 20 40 I = 330 E = 80 O = 280

  11. FPC = I * W1 + E * W2 + O * W3 Function Point Count FPC W1 = .58 W2 = 1.66 W3 = .26 Weighting Constants e.g FPC=330*.58+80*1.66+280*.26 = 303 I = 330 E = 80 O = 280 2c Sum of Weighted Counts = System Size Values of Constants Depend on Organisation and Complexity of Transactions

  12. Data Communication Distributed Functions Performance Objectives Heavily Used Configuration Transaction Rate On-Line Data Entry End User Efficiency Complex Processing On-Line Update Design for Reusability Installation Ease Operational Ease Multiple Sites Facilitate Change Interface to Systems Security/Privacy User Training Third Party Use Documentation 3 Rate System Complexity Rate each Complexity Factor between 0 (Low) and 5 (High) e.g Min = 0 Max = 95 but say TCF=56

  13. FPC=330*.58+80*1.66+280*.26 = 303 4 Calculate Adjusted FP Count Total Technical Complexity Factor (TCF) = sum of complexity factors Adjusted FPC (AFPC) = ( 0.65 + 0.005 * TCF ) * FPC TCF=56 e.g AFPC =(.65+0.005*56)*303=282

  14. e.g AFPC =(.65+0.005*56)*303=282 5 Determine Effort Effort = AFPC / Productivity Man Days Well Specified & Familiar System 1.5 FP/Man Day Poorly Specified but Familiar System 1.1 FP/Man Day Well Specified but Unfamiliar System 0.7 FP/Man Day Poorly Specified & Unfamiliar System 0.5 FP/Man Day Average Productivity 0.8 FP/Man Day e.g Effort = 282/.7=410 man days

  15. 0.5 Delivery Rate = 0.45 * AFPC e.g AFPC =(.65+0.005*56)*303=282 6 Determine Elapsed Time Elapsed Time = AFPC / Delivery Rate (Constants adjusted to suit organisation) e.g Delivery Rate = .45*282^0.5 = 7.5 Elapse Time = 282/7.5=37 .5 weeks

  16. 7 Effort & Elapsed Time/Stage

  17. 8 Adjust Estimates Adjust for such risks as…. • system size being significantly large • Problem structure allow for • illdefined procedures, lack of user committment • major changes for user, users scattered, users unavailable • Technology which is new, new methods, use of CASE tool • Time and manpower constraints • SCF=available weeks/estimated elapse (is <.5 slim chance)

  18. Assess the System Size in Function Points • Rate the System Complexity • Calculate the 'Adjusted Function Point Count' • Decide on Expected Productivity Rate for the Project • Calculate Effort in Man Days • Calculate Elapsed Time in Days • Calculate by Stage/Phase • Adjust for risks and constraints FPA - The Steps

  19. Conclusion Good starting point for a transaction processing / information systems Needs to be calibrated to suit organisation Used by vendors to check the validity of quotes by suppliers Available in Software Tools

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