Quantitative Schedule Risk Analysis — completion S-curve, P50 and P80
Cumulative probability curves from a Monte Carlo schedule risk analysis of a CPM network, pre- and post-mitigation, reading off the confidence in the deterministic finish date and the P50 and P80 dates used to set schedule contingency, as required by AACE RP 57R-09.
Make it your own.
title: Quantitative schedule risk analysis — completion date distribution
subtitle: 5,000 iterations, Latin hypercube, on a 412-activity Level-3 network
x: Project completion (week after award)
y: Cumulative probability (%)
x limits: 98 .. 126
y limits: 0 .. 100
grid: both
legend: bottom
line "Pre-mitigation (register as assessed)" colour: red curve: monotone
100 0
102 1
104 5
106 12
108 22
110 33
112 45
114 56
116 67
118 76
120 84
122 90
124 94
line "Post-mitigation (agreed actions delivered)" colour: blue curve: monotone
100 1
102 4
104 12
106 24
108 38
110 50
112 62
114 73
116 82
118 89
120 94
122 97
124 99
note: Three-point durations on 96 risk-loaded activities plus 7 correlated risk events; correlation set at 0.3 within each discipline.
note: The deterministic CPM finish is week 104. Post-mitigation it carries 12% confidence, pre-mitigation 5%. That is the usual finding, and the reason a deterministic date is not the date you commit.
note: Post-mitigation P50 = week 110, P80 = week 116. Pre-mitigation P50 = week 113, P80 = week 119. The agreed mitigations are worth 3 weeks at both confidence levels.
note: Holding an 80% commitment needs 12 weeks of schedule contingency measured from week 104, of which 6 weeks is already implied by the P50.
note: These curves are the run's output only. They carry no allowance for the two register entries marked unquantified, so they are a floor on exposure, not a bound on it.