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Kim.yunjin

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Kim.yunjin

  1. 1. Joint Confidence Level for Small Projects Yunjin, Kim, Alberto Ortega, and Yolanda Cuevas Jet Propulsion Laboratory California Institute of TechnologyPresented at the PM Challenge 2011Conference, February 9-10, 2011, Long Beach, California
  2. 2. Agenda• Fundamentals of Joint Confidence Level (JCL) – Cost-schedule relationship – Importance of the probability density function for schedule activities – Simple examples• NuSTAR example – NuSTAR JCL process – NuSTAR JCL results – Lessons learned• Use of JCL for subsystems• Conclusions02/09/2011 2
  3. 3. What is Joint Confidence Level (JCL)?• Official definition of JCL (from JCL FAQ from NASA HQ) – The probability that cost will be equal or less than the targeted cost and schedule will be equal or less than the targeted schedule date. – A process and product that helps inform management the likelihood of a projects’ programmatic success. – A process that combines a projects’ cost, schedule, and risk into a complete picture.• NASA policy for JCL (NPD 1000.5) – Joint cost and schedule confidence levels are to be developed and maintained for the life cycle cost and schedule associated with the initial lifecycle baselines (such as project baselines at KDP-C).02/09/2011 3
  4. 4. Joint Confidence Level (JCL) Process Used for NuSTAR Mission• Inputs – Resource loaded schedule • Summary project schedule • Burn rate for each cost element – Probability density functions for schedule activities – Probability density functions for cost elements• Monte Carlo simulation to produce a two dimensional (cost and schedule) probability density function for cost/schedule success P (c, s) where c cost, s schedule cs• Outputs C R Probability of cost less than CR Pr(c CR , s) Pcs (c, s) dc 0 SR Probability of schedule less than S R Pr(c, s SR ) Pcs (c, s ) ds 002/09/2011 4
  5. 5. Schedule A Simple Example (1) uncertainty• Consider a single schedule activity 100 days & $5k/working days – Duration: 100 working days • Schedule risk probability density function = uniform probability over [-10 working days, +30 working days] – Burn rate = $5k/ working day 700 650 Cost (in $k) 600 70% schedule = 118 working days 550 500 70% cost = $590k 450 400 80 90 100 110 120 130 140 Schedule Duration (in working days)02/09/2011 5
  6. 6. A Simple Example (2) Cost Schedule uncertainty uncertainty• Consider a single schedule activity 100 days & $5k/working days – Duration: 100 working days • Schedule risk probability density function = uniform probability over [-10 working days, +30 working days] – Burn rate = $5k/ working day • Cost probability density function = uniform probability over [0%, +30%] 900 850 800 70% schedule = 117 Cost (in $k) 750 working days 700 650 70% cost = $676k 600 550 500 450 400 80 90 100 110 120 130 14002/09/2011 6 Schedule Duration (in working days)
  7. 7. A Simple Example (3)• Consider a slightly more complex case shown below. – Total schedule: 220 working days – Burn rate • Task 1: $15k/day • Task 2: $20k/day • Task 3: $10k/day • Task 4: $5k/day – For all four schedule activities • Schedule PDF = uniform over [-10 working days, +30 working days] • Cost PDF = uniform over [0%, 30%] 100 working days Task 1 Task 2 (100 working days) 20 Task 3 (80 working days) 40 Task 4 (90 working days) 3002/09/2011 7
  8. 8. A Simple Example (4) 8000 7500 Cost (in $k) 7000 70% schedule = 232 6500 working days 6000 5500 70% cost = $6371k 5000 4500 150 170 190 210 230 250 270 290 Schedule Duration (in working days)• Correlation coefficient – Cost • Task 1: 0.537, Task 2: 0.755, Task 3: 0.349, Task 4: 0.162 – Schedule • Task 1: 0.766, Task 2: 0.547, Task 3: 0.099, Task 4: 0.13002/09/2011 8
  9. 9. PDF Selection for JCL• It is obvious that the most important information for JCL is the probability density function for each schedule activity.• Two probability density functions that we considered are – Uniform PDF = Minimum Maximum – Triangle PDF = ( Minimum Maximum• A truncated Gaussian PDF can also be used based on the central limit theorem.02/09/2011 9
  10. 10. Determination of Maximum and Minimum Values of PDF• To specify uniform PDF or triangular PDF, we have to specify both the maximum and the minimum values.• To be conservative, we can use the baseline schedule and budget to specify the minimum value.• The maximum value can be specified based on the project risk list.02/09/2011 10
  11. 11. NuSTAR Mission OverviewSalient Features• PI-led (PI: Fiona Harrison, Caltech) SMEX mission• NuSTAR will carry the first high-energy X-ray focusing telescope• NuSTAR partners include Caltech, JPL, GSFC, Orbital, ATK, UCB, DTU, KSC, Columbia University and ASI• JPL managed project• Category 3, Class D (enhanced) mission• Launch readiness date: November 15, 2011 Goddard Space Flight Center Kennedy Space Flight Center • Launch date: February 3, 2012• Science operations: 2 yearsScience• NuSTAR will open a new window on the Universe by making maps of the high-energy X-ray sky (6 keV to 79 keV ) that are more than 100 times deeper than from any previous mission• Objective 1: Determine how massive black holes are distributed through the cosmos, and how they influence the formation of galaxies like our own• Objective 2: Understand how stars explode and forge the elements that compose the Earth• Objective 3: Determine what powers the most extreme active black holes 02/09/2011 11
  12. 12. NuSTAR JCL Process (1)• The NuSTAR JCL was completed in November 2009.• From the project integrated master schedule (about 3500 lines), a summary schedule (about 162 lines) was developed. – This step is critical to the efficient implementation of JCL. – The schedule includes the actual performance and costs incurred through August 2009. – The summary schedule must maintain the work flow and the schedule network accurately. – The summary schedule was reviewed several times to validate the accuracy.• The cost information was included in MS project based on the burn rates of schedule activities.• The schedule/cost probability density functions were determined by reviewing the project risk list. – These probability density functions were also reviewed with the system managers.02/09/2011 12
  13. 13. NuSTAR JCL Process (2)• A “penalty” task was created in the schedule in the form of a hammock task to capture the “marching army” costs associated with supporting a launch past its planned date .• Monte Carlo simulations were performed using @risk add-on tool to Microsoft Project.02/09/2011 13
  14. 14. NuSTAR JCL Results (1) 70% confidence for Launch = 11/9/2011 70% confidence for the LCC = $110,839,400 Project Cost $125,000,000 $120,000,000 $115,000,000 $110,000,000 $105,000,000 $100,000,000 $95,000,000 $90,000,000 8/5/11 9/24/11 11/13/11 1/2/12 2/21/1202/09/2011 14
  15. 15. NuSTAR JCL Results (2) $105.2M has a confidence level of 25%. $110.8 has a confidence level of 70%02/09/2011 15
  16. 16. NuSTAR JCL Results (3) Key Cost Drivers Instrument Cost Uncertainty 0.748 Spacecraft Cost Uncertainty 0.592 OSC OBS Integration and Env Testing 0.305 Flight Optics Assembly 0.141 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.802/09/2011 16
  17. 17. NuSTAR JCL Results (4) Current launch date of 8/15/11 is slightly less than 5%. 70% confidence of 11/9/11 projects close to a 3 month slip.02/09/2011 17
  18. 18. NuSTAR JCL Results (5) Key Schedule DriversOSC OBS Integration and Env Testing 0.669 Flight Optics Assembly 0.531 Istrument I&T Schedule 0.237 Structure Fabrication, Assy and test 0.099 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.802/09/2011 18
  19. 19. Lessons Learned for Determining Schedule/Cost PDF• The PDFs used for the NuSTAR JCL were too optimistic for heritage hardware.• The PDFs did not include typical test failures and engineering mistakes accurately.• When we derived the PDFs, we should have considered the historical data.• Overall, the schedule PDFs were optimistic.02/09/2011 19
  20. 20. JCL Concept Applied to Subsystem Schedule/Cost Assessment (1)• The JCL concept can be used to estimate the subsystem delivery date and the cost.• An example is shown below. – This assessment was done in early September 2010. – The acceptance test started in late September 2010. – Schedule probability density functions are shown in the diagram. – The cost probability density function is [0%, 30%] uniform. The burn rate is $15k/day . Acceptance test Integration Vibration test (10 working days (10 working days (8 working days PDF =[0,10] uniform) PDF =[0,10] uniform) PDF =[0,3] uniform) Function check-out & Preparation for shipping alignment (3 working days (15 working days PDF =[0,1] uniform) PDF=[0,10] uniform)02/09/2011 20
  21. 21. JCL Concept Applied to Subsystem Schedule/Cost Assessment (2)• Subsystem JCL in September 2010 1400 1300 1200 70% schedule = 65.8Cost (in $k) 1100 working days 1000 900 70% cost = $1140.5k 800 45 50 55 60 65 70 75 80 85 Schedule Duration (in working days)02/09/2011 21
  22. 22. JCL Concept Applied to Subsystem Schedule/Cost Assessment (3)• The subsystem JCL was repeated in October 2009 based on the acceptance test progress. – The baseline schedule and the schedule probability density functions have been revised as shown in the diagram. – The cost probability density function is [0%, 20%] uniform. The burn rate is $15k/day . Acceptance test Integration Vibration test (25 working days (15 working days (8 working days PDF =[0,5] uniform) PDF =[0,5] uniform) PDF =[0,3] uniform) Function check-out & Preparation for shipping alignment (3 working days (15 working days PDF =[0,1] uniform) PDF=[0,15] uniform)02/09/2011 22
  23. 23. JCL Concept Applied to Subsystem Schedule/Cost Assessment (4) • Subsystem JCL repeated in October 2010 based on the acceptance test progress 1600 1500 1400Cost (in $k) 70% schedule = 83.5 1300 working days 1200 70% cost = $1340.3k 1100 1000 60 65 70 75 80 85 90 95 100 Schedule Duration (in working days) 02/09/2011 23
  24. 24. JCL Concept Applied to Subsystem Schedule/Cost Assessment (5) • Comparison between the September JCL and the October JCL September October 70% schedule = 65.8 working days 70% schedule = 83.5 working days 70% cost = $1140.5k 70% cost = $1340.3k 1400 1600 1300 1500 1200 1400 Cost (in $k)Cost (in $k) 1100 1300 1000 1200 900 1100 800 1000 45 50 55 60 65 70 75 80 85 60 65 70 75 80 85 90 95 100 Schedule Duration (in working days) Schedule Duration (in working days) 02/09/2011 24
  25. 25. Conclusions• The NuSTAR JCL demonstrated that JCL can be performed efficiently using a summary schedule derived from the project integrated master schedule.• The most important step in JCL is driving the probability density function for each schedule activity based on the project risk list. – In addition to the project risk list, historical data should be considered if available.• The NuSTAR JCL accurately predicted key schedule/cost drivers.• The JCL concept can be used to estimate the subsystem delivery date and cost.02/09/2011 25

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