Software Estimation

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Software Estimation

  1. 1. Software Estimation Presented by – Dinesh Singh
  2. 2. Agenda <ul><li>Importance of Software Estimation </li></ul><ul><li>Type of Estimation </li></ul><ul><li>Estimation Tools/Techniques </li></ul><ul><li>Which Technique to use and when </li></ul><ul><li>Estimation Process </li></ul><ul><li>Estimation Tips </li></ul><ul><li>Explanation of Few Technique </li></ul><ul><li>Estimation Metrics </li></ul>
  3. 3. Importance of Software Estimation <ul><li>Budgeting & Decision Making </li></ul><ul><li>Forecast Profitability (IRR, NPV, Payback period, Benefit cost ratio , opportunity cost) </li></ul><ul><li>Reliable Resource Planning & Scheduling </li></ul><ul><li>Satisfied Customer </li></ul><ul><li>Under Estimation lead to loss, over estimation may loose business </li></ul><ul><li>Process Improvement </li></ul><ul><li>Fuzzy estimates can only lead to fuzzy project plans </li></ul>
  4. 4. Type of Estimation <ul><li>( Size, Efforts , Schedule and cost) </li></ul><ul><li>Initiation (order of magnitude -25 to +75) </li></ul><ul><li>Budgetary (Planning -10 to +25) </li></ul><ul><li>Definitive ( Requirement -5 to +10) </li></ul><ul><li>Intermediate </li></ul><ul><li>Post construction </li></ul>
  5. 5. Estimation Tools/Techniques <ul><li>Top Down </li></ul><ul><ul><li>Expert Judgment ( Experience & Historical data, Use Delphi method) </li></ul></ul><ul><ul><li>Analogous ( On similar projects, Top down) </li></ul></ul><ul><ul><li>Three point Analysis - (o+4m+p)/6 </li></ul></ul><ul><ul><li>Reserve Analysis (Contingency, Management) </li></ul></ul><ul><li>Bottom UP </li></ul><ul><ul><li>Function Point Analysis </li></ul></ul><ul><ul><li>Use Case Point </li></ul></ul><ul><ul><li>Object Point Analysis </li></ul></ul><ul><ul><li>Program Complexity Method </li></ul></ul><ul><ul><li>COCOMO-Constructive Cost Model (Based on LOC) </li></ul></ul>
  6. 6. Which Technique to use and when <ul><li>Function Point Analysis/Expert/ three point/reserve /Analogous </li></ul><ul><ul><li>System is to be developed from scratch </li></ul></ul><ul><ul><li>Scope is available at broad level only </li></ul></ul><ul><ul><li>Person with high project management experience </li></ul></ul><ul><li>Use Case Point / Object Point / PCM / Base sizing </li></ul><ul><ul><li>Functionality is clear up to screen level </li></ul></ul><ul><ul><li>Enhancement of existing system </li></ul></ul><ul><ul><li>Scope is very clear </li></ul></ul><ul><ul><li>Person with good technical knowledge </li></ul></ul>
  7. 7. Estimation Process Collect Initial Requirement Estimate Size Estimate Efforts Produce Schedule Approve Estimate Develop Product Approved Actual Analyse Estimation Process Historical Project Data Resource Availability
  8. 8. Tips <ul><li>Create Details Work Break down structure till manageable level </li></ul><ul><li>Spend enough time to do proper Estimate </li></ul><ul><li>Involve Developer </li></ul><ul><li>Use more than one people and technique to estimate separately ( for large projects) </li></ul><ul><li>Use at least one estimation tool </li></ul><ul><li>Mine historical information to tune your estimation capability </li></ul><ul><li>Mention Dependencies and assumptions </li></ul>
  9. 9. Function Point Analysis (FPA) <ul><li>FPA </li></ul><ul><ul><li>ILF ( Logical Entity resides on internal system) </li></ul></ul><ul><ul><ul><li>e.g Customer Details </li></ul></ul></ul><ul><ul><li>EIF ( External Entity referred by system) </li></ul></ul><ul><ul><li>EI ( User interaction screen , it may have ILF) </li></ul></ul><ul><ul><li>EQ ( Queries , does not update ILF or EIF) </li></ul></ul><ul><ul><li>EO (Across Application eg XML, can update ILF &EIF) </li></ul></ul><ul><ul><ul><li>RET ( Normalization of the ILF & EIF) </li></ul></ul></ul><ul><ul><ul><li>DET ( User recognized data element type) </li></ul></ul></ul><ul><ul><ul><li>FTR ( Files used in transitions) </li></ul></ul></ul>
  10. 10. Function Point Analysis (FPA) <ul><li>ILF Function point </li></ul><ul><li>EIF Function point </li></ul>15 15 10 6 + RETs 15 10 7 2 - 5 RETs 10 7 7 1 RET 51+ DETs 20 - 50 DETs 1-19 DETs   10 10 7 6 + RETs 10 7 5 2 - 5 RETs 7 5 5 1 RET 51+ DETs 20 - 50 DETs 1-19 DETs  
  11. 11. Function Point Analysis (FPA) EI Function point 6 6 4 3 + FTRs 6 4 3 2 FTRs 4 3 3 1 FTR 16 + DETs 5 -15 DETs 1- 4 DETs  
  12. 12. Function Point Analysis (FPA) EO Function point 7 7 5 4 + FTRs 7 5 4 2 - 3 FTRs 5 4 4 1 FTR 20+ DETs 6- 19 DETs 1-5 DETs  
  13. 13. Function Point Analysis (FPA) EQ Function point 6 6 4 4 + FTRs 6 4 3 2 - 3 FTRs 4 3 3 1 FTR 20+ DETs 6-19 DETs 1-5 DETs  
  14. 14. Function Point Analysis (FPA) <ul><li>Function point calculation </li></ul><ul><ul><li>UFPC = Total of all function points </li></ul></ul><ul><ul><li>Degree of Influence on 14 points (Response time, transaction rate, ..) </li></ul></ul><ul><ul><li>VAF = 0.65 + (TDI *0.01) </li></ul></ul><ul><ul><li>Function point = UFPC * VAF </li></ul></ul><ul><li>Efforts Estimate </li></ul><ul><ul><li>3 GL - 0.5 to 1 FP/day </li></ul></ul><ul><ul><li>4 GL - 1 to 1.5 FP/day </li></ul></ul><ul><ul><li>5 GL - 2 to 5 FP/day </li></ul></ul>
  15. 15. <ul><li>FPA Template </li></ul><ul><li>OPE Template </li></ul>Exercise & Demo
  16. 16. Three Magic formulae <ul><li>Three Magic formulae </li></ul><ul><ul><li>Project Duration = 2.5 * (Cube Root of Work Months) </li></ul></ul><ul><ul><li>Optimum Staffing Size = Square Root of Work Months </li></ul></ul><ul><ul><li>Minimum Duration = 0.75 * (Cube Root of Work Months) </li></ul></ul>
  17. 17. Estimation Metrics <ul><li>Effort Slippage- ( Actual – Planned)*100/Planned </li></ul><ul><li>% Efforts used - Actual*100/Planned or budgeted </li></ul><ul><li>% Rework efforts- Rework*100 / Total </li></ul><ul><li>%Review & testing – Review & testing *100/ Total </li></ul>
  18. 18. Q & A
  19. 19. Thanks

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