What QSRA tells you
- Confidence dates: P50, P80 and P90 finish dates, instead of one deterministic date.
- Schedule contingency: how much time is needed between the plan and the date you commit to.
- Risk drivers: a tornado chart ranking the activities and risks that move the finish date most.
- Mitigation value: how many weeks each mitigation buys, which tells you where to spend money.
The six steps
Schedule health check
Fix open ends, hard constraints and broken logic before any simulation.
Uncertainty ranges
Apply three-point estimates to durations, ideally calibrated from project data.
Risk mapping
Map discrete risk events from the risk register onto the activities they affect.
Correlation
Link activities that move together, so the model does not understate total risk.
Monte Carlo simulation
Run thousands of iterations in Safran Risk or Primavera Risk Analysis.
Decision readout
Report the P80 date, the drivers and the mitigations in terms a board can act on.
QSRA, SRA and QRSA
SRA (schedule risk analysis) is often used for the same thing; the Q stresses that the analysis is numerical. QRSA is a common misspelling of QSRA. QCRA is the cost equivalent, and the two combined give an integrated cost and schedule risk analysis.
Where QSRA is required
In the UK, major programmes use QSRA at funding and assurance gates, and NEC4 contracts put the programme at the centre of compensation events. In the GCC, owners on oil and gas, rail and giga-projects increasingly expect a QSRA before approving a baseline, with shutdown windows, LSTK terms and summer working limits modelled explicitly.
Common mistakes
- Simulating a broken schedule. Poor logic gives a confident wrong answer.
- Workshop guesses as inputs. Unchallenged three-point estimates are usually optimistic.
- Ignoring merge bias. Parallel paths converging on one milestone delay the finish in ways the critical path does not show.
Related terms
