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Estimate software projects
                 Faster, Cheaper and Better!

    Can parametric estimating ‘beat’ the experts?



                      H.S. van Heeringen
@haroldveendam        Brussels, May 2012
Overview
• Sogeti
• Expert vs. Parametric Estimates
• Chalenge for parametric estimates
• Estimating Wizard
• Study: Expert accuracy vs. Parametric accuracy




                                       2
Sogeti
• Sogeti is the ‘local IT’ brand of Capgemini
• Over 20.000 people in 15 countries
 − Belgium, Denmark, Finland, France, Germany, India,
   Ireland, Luxemburg, Netherlands, Norway, Spain, Sweden,
   Switzerland, UK and the US.

• Sogeti Nederland: ca. 3.000 people
• Local IT service provider:
 − Close to the clients;
 − Our mission is to be a leading provider of professional
   technology services. Our vision is to be perceived as the
   best supplier on each local market;
 − Tmap (test), DYA (architecture), ViNT (research), etcetera.
                                                  3
Project Estimates
• Two types of project estimation:
 − Expert estimation
 − Parametric estimation

• Expert estimates
 − Knowledge and experience of experts
 − Assign effort hours to tasks (bottom-up)
 − Subjective, but always applicable

• Parametric estimates
 − Size measurement, historical data, CER’s and tooling
 − Size measurement methods: NESMA FPA, COSMIC, IFPUG
 − Objective, but well documented specifications required

                                                    4
Software Size measurement
• Software is hard to measure before the project
  starts
• But size is usually the main cost driver
• Best practice: measure functionality requested
  by the users
 − NESMA / IFPUG / COSMIC function points

• Objective, verifiable, repeatable methods
• Although ISO standards, there is always an
  inaccuracy margin
 − Documentation is not complete or not detailed enough
 − Measurers don’t have the required level of expertise
 − During the projects, changes will happen
                                                  5
Comparing the two types
• Expert Estimates
 − Bottom-up estimation
 − Usually optimistic (up to 30% under estimation is common)
   ◦ Forgotten activities
   ◦ Hard to defend
   ◦ The expert is not going to do all the work
   ◦ The expert may not be an expert on the new project



• Parametric Estimates
 − Top-down estimation
 − Estimating & Performance Measurement process needed
 − Effort = size * Productivity
   ◦ Size is objectively measureable (COSMIC, FPA)
   ◦ Productivity from historical data (organization / ISBSG)
                                                          6
Expert Estimation
 Task– Code and en Unit test of module XYZ

                                            90%   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   24   hours
                                            75%   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   22   hours
100%                      Realistic estimate50%   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   20   hours
                                            10%   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   18   hours
                          Expert estimate 0%      .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   16   hours
 Probability




                                                                                  .   .   .   .   .   .   .   .   14   hours
                                                                                  .   .   .   .   .   .   .   .   12   hours
                                                                                  .   .   .   .   .   .   .   .   10   hours
                                                                                  .   .   .   .   .   .   .   .    8   hours
                                                                                  .   .   .   .   .   .   .   .    6   hours
                                                                                  .   .   .   .   .   .   .   .    4   hours
 0%                                                                               .   .   .   .   .   .   .   .    2   hours
                          Effort


               Expert Estimate: 1st possibility of success
                    50/50 median result                                               7
Cost of high and low estimates

    Non-linear extra costs
    -Planning errors
    -team enlargement more expensive, not faster
    -Extra management attention / overhead
    -Stress: More defects, lower maintainability !!




                                                 Linear extra kosten
                                                 Extra hours will be used




                                                           8
Sogeti AS SEC
• Division Application Services
 − projects and maintenance (fixed price/ fixed date)
• CoE Sizing, Estimating & Control (SEC)
 − Parametric estimation, control, historical data collection
 − External services, project estimation, benchmarking,
   consultancy


• CoE: Microsoft, Java, Oracle
 − Onshore / offshore teams
 − Expert estimates (technical architects / programmers)


• Challenge of parametric and expert estimate
                                                    9
Challenge – ‘sell parametric estimates’
• Project/Bid management still believe experts
  more than parametrics
 − ‘More detail must mean more accurate, right’?
 − ‘This project is very different from past projects’
 − ‘I see that we don’t get any function points for module XYZ,
   but we have to do a lot of work for that!’
 − ‘I think the project is quite easy and I think that the
   parametric estimate overestimates the effort’


 − But what about: team size, duration, forgotten activities,
   past performance.

• How can we convince project management ??
                                                    10
Software equation
            Size/productivity                                   constant
         = Effort   1/3
                          * duration4/3                         Tradeoff
Effort




                          Plan A: 6 months, 4.500 hours



                                    Plan B: 7 months, 2.400 hours




                             Duration                      11
Project at different durations
                              Plan A
                              Duration: 6 months
                              Effort: 4.500 hours
                              Max. team size: 5,8 fte
                              MTTD: 1,764 days
Team size (fte)




                                          Plan B
                                          Duration: 7 months
                                          Effort: 2.400 hours
                                          Max. team size: 2,7 fte
                                          MTTD: 2,816 days




                                 Which duration have the experts in
                  Duration       mind??                   12
Size and productivity being constant
Assignment 2005
• Before 2005: estimation maturity level = 1
• Build estimation instrument
 − Gain time and effort in estimating bids
 − Accurate enough to depend and rely on
 − Flexible:
   ◦ Estimate onshore / offshore and hybrid projects
   ◦ Calculate different test strategies
   ◦ Take into account complexity
   ◦ Implement Deming cycle (PDCA)


• Give scenario’s for duration !!!
                                                   13
First version Estimating Wizard (2005)
• Try to put the duration / effort tradeoff in a
  model
 − Tuned with experience data


 Hour/FP: Average Complexity
 Duration in months        3½    4     4½    5     5½    6     6½    7     7½    8

 0-250 FP                 10,1   8,9   8,1   7,7   6,9
 250-500 FP                      9,1   8,0   7,3   6,9   6,2
 500-750 FP                            8,6   7,6   6,9   6,5   5,9
 750-1000 FP                                 8,3   7,3   6,6   6,3   5,6
 1000 -1250 FP                                     8,1   7,1   6,5   6,2   5,5
 1250 - 1500 FP                                          7,9   6,9   6,3   6,0   5,4




                                                                     14
Estimating Wizard 2011

Estimating Wizard                                Powered by: Sizing, Estimating & Control                Data version: 24-11-2010                    Model version: 17

Input
Functional design parameters
Functional Design                   Yes                                                      Step 1: Is there a functional design phase?
Overlap                 Yes, calculated                         5                            Step 2: In case of overlap between the functional design phase and building
                                                                                                     to let the wizard calculate the overlap, or to enter the number of we
Language                              English                                                Step 3: Enter the language in which the functional design should be written.
Availability key users               Normal                                                  Step 4: Enter the availability-rate of the key users.
Location                         Sogeti office                                               Step 5: Enter the location where the functional design should be written.

Build and test parameters
Development tool                         Java                                                Step 6: Select the development tool.

                                    Onshore              Offshore
C onstruction                           35%                   65%                            Step 7: Enter the percentage of construction work that is done onshore.
Translation FD required                   No                                                 Step 8: Is a translation of the functional design required.

System test approach            TMap Medium                                                  Step 9: Select the TMapfactory system test approach.
System test strategy      Scripting and design NL, excecution in India                      Step 10: Select the system test strategy.

Tools/methodologies                 Unknown                                                 Step   11:   Rate   the   level of tools and methodologies to be used for the develop
C omplexity                         Unknown                                                 Step   12:   Rate   the   technical complexity of the project.
Development team                    Unknown                                                 Step   13:   Rate   the   competence, experience and skill level of the development
Reuse                               Unknown                                                 Step   14:   Rate   the   quantity and complexity of integrating reused, unmodified

General parameters
Size                                      643 C OSMIC                                       Step 15: Enter the functional size and select a unit of size
                                                                                                     (FP= function points, C FP=C OSMIC functionpoints).
Start date                         01-01-11                                                 Step 16: Enter the start date of the project.
Risk surcharge (%)                       10 %                                               Step 17: Enter the risk surcharge percentage.
Warranty (%)                              4 %                                               Step 18: Enter the warranty surcharge percentage.
Organization type                   Banking                                                 Step 19: C hoose the organization type.
Quality documentation                     6                                                 Step 20: Rate the quality of the documentation.
Non functional req.       Average (0)                                                       Step 21: What influence do the non functional requirements have on the effo
Scenario interval                       2,0                                                 Step 22: Enter the number of weeks for the step size between the seven sce

                                                                                                                                        15
EW - output
 • Functional Design – no schedule scenarios
   Functional design phase
   Duration in weeks                      17,6
   Design complete                     4-05-11
   Total effort                          1.975
   Effort per FP                          2,53
   Effort cost                       € 208.531
   Additional cost                    € 14.815
   Totaal cost                       € 223.346
   C ost per FP                          € 286
   Average team size                      2,80




Data altered due to company security reasons     16
EW - output
  • Main build – 7 schedule scenarios
 Build and test phase
 Duration in weeks              20,0        22,0        24,0         26,0        28,0             30,0       32,0
 Start phase                18-02-11    18-02-11    18-02-11    18-02-11     18-02-11         18-02-11   18-02-11
 Effort                        9.794       6.690       4.723        3.429       2.550            1.935      1.495
 Effort per FP                 28,06       19,17       13,53         9,83        7,31             5,54       4,28
 Effort cost               € 550.720   € 376.152   € 265.590   € 192.826    € 143.360        € 108.787   € 84.036
 Additional cost            € 56.446    € 41.090    € 31.364     € 24.963    € 20.611         € 17.570   € 15.393
 Totaal cost               € 607.167   € 417.242   € 296.954   € 217.789    € 163.972        € 126.357   € 99.428
 C ost per FP                € 1.740     € 1.196       € 851        € 624       € 470            € 362      € 285
 Average team size             12,24        7,60        4,92         3,30        2,28             1,61       1,17

 Risk and warranty
 Risk hours                      834         586         429         325          255              205         170
 Risk cost                  € 54.301    € 39.107    € 29.484    € 23.150     € 18.845         € 15.836    € 13.682
 Warranty hours                  209         146         107          81           64               51          43
 Warranty cost              € 13.575     € 9.777     € 7.371     € 5.788      € 4.711          € 3.959     € 3.420

 Total
 Duration in weeks              27,0        29,0        31,0        33,0         35,0             37,0        39,0
 Delivery for acceptance     8-07-11    22-07-11     5-08-11    19-08-11      2-09-11         16-09-11    30-09-11
 Total effort                 11.470       8.055       5.892       4.469        3.501            2.825       2.340
 Effort per FP                 32,87       23,08       16,88       12,80        10,03             8,09        6,71
 Totaal cost               € 746.634   € 537.717   € 405.400   € 318.319    € 259.120        € 217.744   € 188.122
 C ost per FP                € 2.139     € 1.541     € 1.162       € 912        € 742            € 624       € 539
 Average team size             10,64        6,96        4,76        3,39         2,50             1,91        1,50
 Average hourly rate            € 65        € 67        € 69        € 71         € 74             € 77        € 80




Data altered due to company security reasons                                            17
Calibrating the model
• Collect historical data
• Use ISBSG data




                            18
ISBSG       (www.isbsg.org)
• International Software Benchmarking Standards
  Group
• Not-for-profit, members are mostly national
  software measurement organizations
 − NESMA, IFPUG, DASMA, JFPUG, GUFPI-ISMA, AEMES, etc.


• New developments & enhancements repository
 − About 6.000 projects now


• Maintenance & Support repository
 − Over 500 applications now

                                            19
Calibrating the model
• Collect historical data
• Use ISBSG data




                            20
Pricing model
• Sogeti Pricing model




                         21
Estimating Wizard 2012
• Mature tool, proven value
• Effort Estimation Relationships are tuned to
  historical data
• Size is the main input parameter, and it takes
  time to measure size
• Parametric estimating is still not done in one
  click, and perceived as expensive by internal
  clients
• Experts are still perceived more credible and in
  most challenges, the expert estimate is taken
•  study: comparing experts and parametrics
                                         22
Can parametrics beat the experts?
• Study of 20 completed projects
• Different sizes, languages, data normalized
 − Expert estimate
 − Estimating Wizard estimate (FP or CFP)
 − Estimates vs. Actual results


• Calculate
 − Effort Accuracy (Effort estimate / Actual effort)
 − Duration Accuracy (Duration Estimate / Actual Duration)
 − Cost Accuracy (Cost Estimate / Actual Cost)

• <1 underestimation, >1 overestimation
                                                       23
Results
                                            Expert                             Estimating Wizard
                           Effort     Duration     Cost      Time Effort      Duration Cost        Time
Project      Size (FP)     Accuracy   Accuracy    Accuracy   Spent Accuracy   Accuracy    Accuracy spent
Project 1            277      0,675      1,545       0,467     30    0,477       1,204     0,501      17
Project 2            359      0,579      0,951       1,139     35    0,707       0,775     1,170      26
Project 3            347      0,589      0,142       0,615     40    1,067       0,996     1,283      14
Project 4          1.178      0,414      0,557       0,312     60    0,774       0,590     0,862      55
Project 5            951      1,430      0,997       0,946     34    1,067       0,877     1,718      24
Project 6            295      0,763      0,857       0,619     26    0,881       1,200     0,845       6
Project 7            790      0,717      0,850       0,976     34    0,926       0,865     1,132      27
Project 8            350      1,258      0,800       1,309     28    1,203       1,096     1,318      20
Project 9            746      0,586      0,296       0,545     34    0,826       0,385     1,953      22
Project 10         2.293      0,766      0,421       0,797     40    0,931       0,632     1,058      14
Project 11           213      0,689      0,453       0,712     32    0,934       0,621     0,921      12
Project 12           563      0,898      0,912       0,911     40    0,892       1,122     1,234      14
Project 13           711      0,541      0,611       0,521     32    0,712       1,321     0,724      18
Project 14         1.248      0,874      0,719       0,877     60    0,923       1,091     1,122      36
Project 15           122      0,912      0,781       0,916     20    0,945       1,092     1,453      12
Project 16           923      0,814      0,721       0,723     24    0,954       1,221     1,122      26
Project 17           512      0,741      0,843       0,729     32    0,823       0,923     0,892      20
Project 18           789      0,621      0,912       0,649     40    0,711       0,945     1,234      24
Project 19           512      0,891      0,512       0,945     20    0,945       1,109     1,101      22
Project 20           732      0,765      1,210       0,799     24    0,865       1,001     0,902      32
                                                                                     24
Estimation Accuracy results
• Average time spent
 − Expert estimate: 34,3 hours
 − Parametric Estimate (including size measurement): 22,1 hours
           Expert Estimate Estimating Wizard Estimate
                    Effort Accuracy
 Average        0,776                 0,878             Closer to 1 means better!
 St.Dev.        0,236                 0,156
 Median         0,752                 0,908

                  Duration Accuracy
 Average       0,755                  0,953
 St.Dev.       0,318                  0,247
 Median        0,791                  0,998

                    Cost Accuracy
 Average       0,775                  1,127
 St.Dev.       0,237                  0,331
 Median        0,763                  1,122                        25
Results
• Expert estimates take a lot of time too!
 − on average 55% more than Parametric Estimates
 − More than 1 expert has to read through all the
   documentation, discussions, meetings, etcetera


• Parametric estimates are more acurate!
 − Effort and duration estimates on average still optimistic, but
   less optimistic than expert estimates
 − Cost estimates are pessimistic, but still closer to actuals
   than Expert estimate


• Experts might win the project, but the result will
  be overruns!                                      26
Cost of high and low estimates

    Non-linear extra costs
    -Planning errors
    -team enlargement more expensive, not faster
    -Extra management attention / overhead
    -Stress: More defects, lower maintainability !!




                                                 Linear extra kosten
                                                 Extra hours will be used




                                                           27
Conclusions
• Estimating wizard
 −   Higher effort estimation accuracy
 −   Higher duration estimation accuracy
 −   Higher cost estimation accuracy (although >1)
 −   Less hours spent than expert estimates
 −   Standard WBS, historical data collection and parameter
     calibration improve the maturity of the process


• Next steps
 − Analyze why costs are overestimated
 − Try to identify the projects where EW estimate is enough
 − Use the results to convince project management and bid
   management to use parametric estimating even more !!

                                                  28
Thank you for your
attention !!

                       @haroldveendam                Local touch - Global reach




Senior Consultant Software Metrics

Sogeti Nederland B.V.
 
NESMA board member
ISBSG president
COSMIC International Advisory Council, representing the
Netherlands
 
T:  +31 (0)88 660 6600 + 3165 (dial)
M:  +31 (0)6 52 32 73 30
e-mail: harold.van.heeringen@sogeti.nl                             29

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ISPA/SCEA conference Brussels 2012

  • 1. Estimate software projects Faster, Cheaper and Better! Can parametric estimating ‘beat’ the experts? H.S. van Heeringen @haroldveendam Brussels, May 2012
  • 2. Overview • Sogeti • Expert vs. Parametric Estimates • Chalenge for parametric estimates • Estimating Wizard • Study: Expert accuracy vs. Parametric accuracy 2
  • 3. Sogeti • Sogeti is the ‘local IT’ brand of Capgemini • Over 20.000 people in 15 countries − Belgium, Denmark, Finland, France, Germany, India, Ireland, Luxemburg, Netherlands, Norway, Spain, Sweden, Switzerland, UK and the US. • Sogeti Nederland: ca. 3.000 people • Local IT service provider: − Close to the clients; − Our mission is to be a leading provider of professional technology services. Our vision is to be perceived as the best supplier on each local market; − Tmap (test), DYA (architecture), ViNT (research), etcetera. 3
  • 4. Project Estimates • Two types of project estimation: − Expert estimation − Parametric estimation • Expert estimates − Knowledge and experience of experts − Assign effort hours to tasks (bottom-up) − Subjective, but always applicable • Parametric estimates − Size measurement, historical data, CER’s and tooling − Size measurement methods: NESMA FPA, COSMIC, IFPUG − Objective, but well documented specifications required 4
  • 5. Software Size measurement • Software is hard to measure before the project starts • But size is usually the main cost driver • Best practice: measure functionality requested by the users − NESMA / IFPUG / COSMIC function points • Objective, verifiable, repeatable methods • Although ISO standards, there is always an inaccuracy margin − Documentation is not complete or not detailed enough − Measurers don’t have the required level of expertise − During the projects, changes will happen 5
  • 6. Comparing the two types • Expert Estimates − Bottom-up estimation − Usually optimistic (up to 30% under estimation is common) ◦ Forgotten activities ◦ Hard to defend ◦ The expert is not going to do all the work ◦ The expert may not be an expert on the new project • Parametric Estimates − Top-down estimation − Estimating & Performance Measurement process needed − Effort = size * Productivity ◦ Size is objectively measureable (COSMIC, FPA) ◦ Productivity from historical data (organization / ISBSG) 6
  • 7. Expert Estimation Task– Code and en Unit test of module XYZ 90% . . . . . . . . . . . . . . . . 24 hours 75% . . . . . . . . . . . . . . . . 22 hours 100% Realistic estimate50% . . . . . . . . . . . . . . . . 20 hours 10% . . . . . . . . . . . . . . . . 18 hours Expert estimate 0% . . . . . . . . . . . . . . . . 16 hours Probability . . . . . . . . 14 hours . . . . . . . . 12 hours . . . . . . . . 10 hours . . . . . . . . 8 hours . . . . . . . . 6 hours . . . . . . . . 4 hours 0% . . . . . . . . 2 hours Effort Expert Estimate: 1st possibility of success 50/50 median result 7
  • 8. Cost of high and low estimates Non-linear extra costs -Planning errors -team enlargement more expensive, not faster -Extra management attention / overhead -Stress: More defects, lower maintainability !! Linear extra kosten Extra hours will be used 8
  • 9. Sogeti AS SEC • Division Application Services − projects and maintenance (fixed price/ fixed date) • CoE Sizing, Estimating & Control (SEC) − Parametric estimation, control, historical data collection − External services, project estimation, benchmarking, consultancy • CoE: Microsoft, Java, Oracle − Onshore / offshore teams − Expert estimates (technical architects / programmers) • Challenge of parametric and expert estimate 9
  • 10. Challenge – ‘sell parametric estimates’ • Project/Bid management still believe experts more than parametrics − ‘More detail must mean more accurate, right’? − ‘This project is very different from past projects’ − ‘I see that we don’t get any function points for module XYZ, but we have to do a lot of work for that!’ − ‘I think the project is quite easy and I think that the parametric estimate overestimates the effort’ − But what about: team size, duration, forgotten activities, past performance. • How can we convince project management ?? 10
  • 11. Software equation Size/productivity constant = Effort 1/3 * duration4/3 Tradeoff Effort Plan A: 6 months, 4.500 hours Plan B: 7 months, 2.400 hours Duration 11
  • 12. Project at different durations Plan A Duration: 6 months Effort: 4.500 hours Max. team size: 5,8 fte MTTD: 1,764 days Team size (fte) Plan B Duration: 7 months Effort: 2.400 hours Max. team size: 2,7 fte MTTD: 2,816 days Which duration have the experts in Duration mind?? 12 Size and productivity being constant
  • 13. Assignment 2005 • Before 2005: estimation maturity level = 1 • Build estimation instrument − Gain time and effort in estimating bids − Accurate enough to depend and rely on − Flexible: ◦ Estimate onshore / offshore and hybrid projects ◦ Calculate different test strategies ◦ Take into account complexity ◦ Implement Deming cycle (PDCA) • Give scenario’s for duration !!! 13
  • 14. First version Estimating Wizard (2005) • Try to put the duration / effort tradeoff in a model − Tuned with experience data Hour/FP: Average Complexity Duration in months 3½ 4 4½ 5 5½ 6 6½ 7 7½ 8 0-250 FP 10,1 8,9 8,1 7,7 6,9 250-500 FP 9,1 8,0 7,3 6,9 6,2 500-750 FP 8,6 7,6 6,9 6,5 5,9 750-1000 FP 8,3 7,3 6,6 6,3 5,6 1000 -1250 FP 8,1 7,1 6,5 6,2 5,5 1250 - 1500 FP 7,9 6,9 6,3 6,0 5,4 14
  • 15. Estimating Wizard 2011 Estimating Wizard Powered by: Sizing, Estimating & Control Data version: 24-11-2010 Model version: 17 Input Functional design parameters Functional Design Yes Step 1: Is there a functional design phase? Overlap Yes, calculated 5 Step 2: In case of overlap between the functional design phase and building to let the wizard calculate the overlap, or to enter the number of we Language English Step 3: Enter the language in which the functional design should be written. Availability key users Normal Step 4: Enter the availability-rate of the key users. Location Sogeti office Step 5: Enter the location where the functional design should be written. Build and test parameters Development tool Java Step 6: Select the development tool. Onshore Offshore C onstruction 35% 65% Step 7: Enter the percentage of construction work that is done onshore. Translation FD required No Step 8: Is a translation of the functional design required. System test approach TMap Medium Step 9: Select the TMapfactory system test approach. System test strategy Scripting and design NL, excecution in India Step 10: Select the system test strategy. Tools/methodologies Unknown Step 11: Rate the level of tools and methodologies to be used for the develop C omplexity Unknown Step 12: Rate the technical complexity of the project. Development team Unknown Step 13: Rate the competence, experience and skill level of the development Reuse Unknown Step 14: Rate the quantity and complexity of integrating reused, unmodified General parameters Size 643 C OSMIC Step 15: Enter the functional size and select a unit of size (FP= function points, C FP=C OSMIC functionpoints). Start date 01-01-11 Step 16: Enter the start date of the project. Risk surcharge (%) 10 % Step 17: Enter the risk surcharge percentage. Warranty (%) 4 % Step 18: Enter the warranty surcharge percentage. Organization type Banking Step 19: C hoose the organization type. Quality documentation 6 Step 20: Rate the quality of the documentation. Non functional req. Average (0) Step 21: What influence do the non functional requirements have on the effo Scenario interval 2,0 Step 22: Enter the number of weeks for the step size between the seven sce 15
  • 16. EW - output • Functional Design – no schedule scenarios Functional design phase Duration in weeks 17,6 Design complete 4-05-11 Total effort 1.975 Effort per FP 2,53 Effort cost € 208.531 Additional cost € 14.815 Totaal cost € 223.346 C ost per FP € 286 Average team size 2,80 Data altered due to company security reasons 16
  • 17. EW - output • Main build – 7 schedule scenarios Build and test phase Duration in weeks 20,0 22,0 24,0 26,0 28,0 30,0 32,0 Start phase 18-02-11 18-02-11 18-02-11 18-02-11 18-02-11 18-02-11 18-02-11 Effort 9.794 6.690 4.723 3.429 2.550 1.935 1.495 Effort per FP 28,06 19,17 13,53 9,83 7,31 5,54 4,28 Effort cost € 550.720 € 376.152 € 265.590 € 192.826 € 143.360 € 108.787 € 84.036 Additional cost € 56.446 € 41.090 € 31.364 € 24.963 € 20.611 € 17.570 € 15.393 Totaal cost € 607.167 € 417.242 € 296.954 € 217.789 € 163.972 € 126.357 € 99.428 C ost per FP € 1.740 € 1.196 € 851 € 624 € 470 € 362 € 285 Average team size 12,24 7,60 4,92 3,30 2,28 1,61 1,17 Risk and warranty Risk hours 834 586 429 325 255 205 170 Risk cost € 54.301 € 39.107 € 29.484 € 23.150 € 18.845 € 15.836 € 13.682 Warranty hours 209 146 107 81 64 51 43 Warranty cost € 13.575 € 9.777 € 7.371 € 5.788 € 4.711 € 3.959 € 3.420 Total Duration in weeks 27,0 29,0 31,0 33,0 35,0 37,0 39,0 Delivery for acceptance 8-07-11 22-07-11 5-08-11 19-08-11 2-09-11 16-09-11 30-09-11 Total effort 11.470 8.055 5.892 4.469 3.501 2.825 2.340 Effort per FP 32,87 23,08 16,88 12,80 10,03 8,09 6,71 Totaal cost € 746.634 € 537.717 € 405.400 € 318.319 € 259.120 € 217.744 € 188.122 C ost per FP € 2.139 € 1.541 € 1.162 € 912 € 742 € 624 € 539 Average team size 10,64 6,96 4,76 3,39 2,50 1,91 1,50 Average hourly rate € 65 € 67 € 69 € 71 € 74 € 77 € 80 Data altered due to company security reasons 17
  • 18. Calibrating the model • Collect historical data • Use ISBSG data 18
  • 19. ISBSG (www.isbsg.org) • International Software Benchmarking Standards Group • Not-for-profit, members are mostly national software measurement organizations − NESMA, IFPUG, DASMA, JFPUG, GUFPI-ISMA, AEMES, etc. • New developments & enhancements repository − About 6.000 projects now • Maintenance & Support repository − Over 500 applications now 19
  • 20. Calibrating the model • Collect historical data • Use ISBSG data 20
  • 21. Pricing model • Sogeti Pricing model 21
  • 22. Estimating Wizard 2012 • Mature tool, proven value • Effort Estimation Relationships are tuned to historical data • Size is the main input parameter, and it takes time to measure size • Parametric estimating is still not done in one click, and perceived as expensive by internal clients • Experts are still perceived more credible and in most challenges, the expert estimate is taken •  study: comparing experts and parametrics 22
  • 23. Can parametrics beat the experts? • Study of 20 completed projects • Different sizes, languages, data normalized − Expert estimate − Estimating Wizard estimate (FP or CFP) − Estimates vs. Actual results • Calculate − Effort Accuracy (Effort estimate / Actual effort) − Duration Accuracy (Duration Estimate / Actual Duration) − Cost Accuracy (Cost Estimate / Actual Cost) • <1 underestimation, >1 overestimation 23
  • 24. Results Expert Estimating Wizard Effort Duration Cost Time Effort Duration Cost Time Project Size (FP) Accuracy Accuracy Accuracy Spent Accuracy Accuracy Accuracy spent Project 1 277 0,675 1,545 0,467 30 0,477 1,204 0,501 17 Project 2 359 0,579 0,951 1,139 35 0,707 0,775 1,170 26 Project 3 347 0,589 0,142 0,615 40 1,067 0,996 1,283 14 Project 4 1.178 0,414 0,557 0,312 60 0,774 0,590 0,862 55 Project 5 951 1,430 0,997 0,946 34 1,067 0,877 1,718 24 Project 6 295 0,763 0,857 0,619 26 0,881 1,200 0,845 6 Project 7 790 0,717 0,850 0,976 34 0,926 0,865 1,132 27 Project 8 350 1,258 0,800 1,309 28 1,203 1,096 1,318 20 Project 9 746 0,586 0,296 0,545 34 0,826 0,385 1,953 22 Project 10 2.293 0,766 0,421 0,797 40 0,931 0,632 1,058 14 Project 11 213 0,689 0,453 0,712 32 0,934 0,621 0,921 12 Project 12 563 0,898 0,912 0,911 40 0,892 1,122 1,234 14 Project 13 711 0,541 0,611 0,521 32 0,712 1,321 0,724 18 Project 14 1.248 0,874 0,719 0,877 60 0,923 1,091 1,122 36 Project 15 122 0,912 0,781 0,916 20 0,945 1,092 1,453 12 Project 16 923 0,814 0,721 0,723 24 0,954 1,221 1,122 26 Project 17 512 0,741 0,843 0,729 32 0,823 0,923 0,892 20 Project 18 789 0,621 0,912 0,649 40 0,711 0,945 1,234 24 Project 19 512 0,891 0,512 0,945 20 0,945 1,109 1,101 22 Project 20 732 0,765 1,210 0,799 24 0,865 1,001 0,902 32 24
  • 25. Estimation Accuracy results • Average time spent − Expert estimate: 34,3 hours − Parametric Estimate (including size measurement): 22,1 hours Expert Estimate Estimating Wizard Estimate Effort Accuracy Average 0,776 0,878 Closer to 1 means better! St.Dev. 0,236 0,156 Median 0,752 0,908 Duration Accuracy Average 0,755 0,953 St.Dev. 0,318 0,247 Median 0,791 0,998 Cost Accuracy Average 0,775 1,127 St.Dev. 0,237 0,331 Median 0,763 1,122 25
  • 26. Results • Expert estimates take a lot of time too! − on average 55% more than Parametric Estimates − More than 1 expert has to read through all the documentation, discussions, meetings, etcetera • Parametric estimates are more acurate! − Effort and duration estimates on average still optimistic, but less optimistic than expert estimates − Cost estimates are pessimistic, but still closer to actuals than Expert estimate • Experts might win the project, but the result will be overruns! 26
  • 27. Cost of high and low estimates Non-linear extra costs -Planning errors -team enlargement more expensive, not faster -Extra management attention / overhead -Stress: More defects, lower maintainability !! Linear extra kosten Extra hours will be used 27
  • 28. Conclusions • Estimating wizard − Higher effort estimation accuracy − Higher duration estimation accuracy − Higher cost estimation accuracy (although >1) − Less hours spent than expert estimates − Standard WBS, historical data collection and parameter calibration improve the maturity of the process • Next steps − Analyze why costs are overestimated − Try to identify the projects where EW estimate is enough − Use the results to convince project management and bid management to use parametric estimating even more !! 28
  • 29. Thank you for your attention !! @haroldveendam Local touch - Global reach Senior Consultant Software Metrics Sogeti Nederland B.V.   NESMA board member ISBSG president COSMIC International Advisory Council, representing the Netherlands   T:  +31 (0)88 660 6600 + 3165 (dial) M:  +31 (0)6 52 32 73 30 e-mail: harold.van.heeringen@sogeti.nl 29

Hinweis der Redaktion

  1. Good afternoon Ladies and Gentlemen. Welcome to this presentation on the estimation of software projects. I’m very glad to be in this conference. Actually, this is the first time that I’m attending a conference that is not completely dedicated to software estimation or software metrics. This presentation is about the differences between expert estimates and parametric estimates.
  2. This is the agenda for the presentation. First I would like to say a few things about the company that I work for, as most of you probably don’t know the name Sogeti. After that, I am going to show the differences between expert estimates and parametric estimates in software projects. I’m working in the field of Parametric Estimates and I want to share one of our main challenges with you. Next I’m going to introduce the Sogeti estimating wizard and of course the results of the study we did on the accuracy differences between expert estimates and parametric estimates.
  3. Ok, first a few remarks on Sogeti. We are a daughter company of Capgemini and we are the local IT brand of Capgemini. Close to our customers, but quite big in total. In the Netherlands, about 3000 people, but over 20.000 worldwide. We are well known for our Crraftsmenship and thought leadership in different areas, like testing, architecture and industry research… but also in parametric estimating (at least in the Netherlands we are)
  4. 1.01 Meten &amp; Begroten dagdeel 1 v1.0 Sogeti Nederland B.V. v1.0
  5. As I mentioned on the previous slide, it’s very important to size the software that has to be realized in an accurate way. As this is actually the main cost driver for all our models and tools. Unfortunately, unlike for instance in the construction industry where one can draw a building plan and then measure the surface or volume and other physical things, software is a non-physical thing. We cannot grab and hold a piece of software and therefore it’s hard to measure. In software industry, a best practice has been evolved over the last few decades to measure the functionality of the requirements that the user wishes to be fulfilled in the software. These requirements should be known beforehand, right? That’s why an ISO standard for functional size measurement methods has been drawn up and a number of functional size measurement methods comply to this standard. In order to be able to use the size measure in collecting historical data, the building of parametric models and the estimation of software projects, of course the method must be objective, repeatable and verifiable. The three methods listed here are all ISO standards and the measure is called function points. However, even the ISO standard does not guarantee a completely accurate result. Functional user requirements are usually described only high level when the bid has to take place and changes are likely to occur during the project.
  6. 1.01 Meten &amp; Begroten dagdeel 1 v1.0 Sogeti Nederland B.V. v1.0
  7. 1.01 Meten &amp; Begroten dagdeel 1 v1.0 Sogeti Nederland B.V. v1.0
  8. Sogeti Nederland B.V.
  9. I am working in the department Sizing, Estimating &amp; Control and I’m involved in the quotations we are giving our customers. We have a number of specialists who are experts in sizing the requirements of the clients. The size of the user requirements is actually a main cost driver in many projects, so this is an important part of our work. When the size is measured, we have the parametric models and tools to estimate characteristics like effort, duration, team size, quality and costs. In our division, every quotation is supported by both a parametric estimation and an expert estimation, which we call technical calculation. The expert calculation is carried out by technical architects in one of our Centers of Excellence. Sogeti Nederland B.V.
  10. Dan kijken we naar een andere belangrijke factor: de doorlooptijd. We nemen als uitgangspunt de software equation die door Putnam senior is gepubliceerd en die ook in de QSM SLIM tooling wordt gebruikt. U ziet de formule staan. Het idee is dat bij een gegeven omvang en een gegeven productiviteit, het altijd mogelijk is om verschillende inspanning / doorlooptijd scenario’s te maken. De omvang is objectief gemeten. De productiviteit komt uit de ervaringscijfers. U ziet hier 2 verschillende plannen staan. Omdat de formule een zwaarder gewicht toekent aan de doorlooptijd is dit een belangrijke factor. De doorlooptijd iets verkorten leidt tot een onevenredige toename van het totaal aantal benodigde uren.
  11. De reden daarvoor wordt duidelijk als we naar deze figuur kijken. Ik heb de twee plannen uit de vorige figuur hier iets verder uitgewerkt. We zien dat we voor plan A een groter team nodig hebben dan voor plan B. Dit team is misschien groter dan u zou verwachten. Dit komt omdat iedere extra persoon in een team de overall productiviteit verlaagd. Er worden extra communicatiepaden gecreëerd en het wordt moeilijker om het project te managen in die zin dat iedereen nuttig aan het werk gehouden moet worden. Een groter team betekent ook meer defects, wat hier tot uiting komt in een lagere mean-time-to-defect. Iedere defect moet worden gelogd, terug naar de bouw, geanalyseerd, opgelost, geunittest en weer aan de systeemtest worden opgeleverd. Veel extra werk per defect dus.
  12. Sogeti Nederland B.V.