Monte Carlo vs. PERT Tutorial Engineering 25 Monte Carlo vs. PERT Tutorial Bruce Mayer, PE Registered Electrical & Mechanical Engineer BMayer@ChabotCollege.edu

NO Time Machines Allowed In the Lecture on Monte Carlo Methods as used in the PERT Prob we allowed NEGATIVES in the Simulation Someone might point out that no matter how hard we work we can not MAKE time We can only USE time! ReDo the simulation withOUT negative Times

Recall WhareHouse PERT chart 1. Project Start 2 3 4 5 6 7 1. Project End A B E F G H C D The Schedule Elements Excavate Foundation Construct Foundation Fabricate PreCast Components Ship PreCast Parts to Building Site Install PreCast Parts on Foundation Build Roof Finish Interior and Exterior Inspect Result

Possibility of Negative Times A Small MeanDuration:StdDev ratio indicates a higher probability of NEGATIVE durations Task ID Task Description Mean Duration (days) Std Dev (days) A Foundation Excavation 3.5 1 B Pour Foundation 2.5 0.5 C Fab PreCast Elements 5 D Ship PreCast Parts E Tilt-Up PreCast Parts 1.5 F Roofing 2 G Finish Work 4 Expected Duration = 17 Days Critical Path in Blue • Note in the circled cases the StdDev:Duration ratio is SMALL: 100%,, 50%, 30%

5000-Trials Look for Negatives

Expected Standard Deviation (RMS) Find the Expected Standard Deviation by GeoMetric (or Pythagorean or RMS) Calculation In This case take the Std Dev from the GATING item A+B to find:

Compare Lack of Time Machine Review and Run Files: Monte_Carlo_Wharehouse_1604.m Can MAKE time Monte_Carlo_Wharehouse_Vectorized.m NO Loops Monte_Carlo_Wharehouse_No_Negatives.m Can NOT make time A “Flux Capacitor”