Glossary
Integrated Cost-Schedule Risk Analysis (QCSRA)
A single Monte Carlo model that analyses schedule and cost risk together, capturing the way schedule slip drives prolongation cost and cost pressure drives schedule compression.
QSRA vs QCRA vs QCSRA — three Monte Carlo techniques compared.
| QSRA (Schedule Risk) | QCRA (Cost Risk) | QCSRA (Integrated) | |
|---|---|---|---|
| What it models | Activity-duration uncertainty + schedule-impact risks | Cost-line uncertainty + cost-impact risks | Both, with their dependencies modelled explicitly |
| Key output | S-curve of completion dates (P50 / P80 / P95) | S-curve of outturn cost (P50 / P80 / P95) | Joint distribution: probability of any (date, cost) pair |
| Captures prolongation cost? | No — schedule slip doesn't drive cost | No — cost is independent of duration | Yes — schedule slip auto-extends cost-loaded prelims, site overheads |
| Captures cost-driven schedule pressure? | No | No | Partial — via correlated risks and shared driver activities |
| Joint P80 reliable? | No — combine two single-axis P80s and you understate joint exposure | Same | Yes — the only technique that gives a defensible joint confidence position |
| Tool support | Safran Risk, Primavera Risk Analysis (PRA), @Risk, Acumen Risk | Same tools, cost-only mode | Same tools — integrated cost-schedule mode |
| AACE reference | 57R-09, 64R-11 | 40R-08, 57R-09 | 57R-09 (the integrated framework) |
| When to use | Schedule confidence is the primary governance question | Cost confidence is primary; schedule already locked | Both governance-critical (most major UK infrastructure programmes) |
Integrated Cost-Schedule Risk Analysis (sometimes called QCSRA) combines QSRA and QCRA into a single model so that the dependencies between time and cost risk are captured explicitly. The central insight is that schedule risk and cost risk are not independent: extended programme duration drives extended preliminaries cost, ongoing site overheads, and potential liquidated damages; cost overruns drive pressure to compress schedule, often introducing schedule risk of their own. Analysing the two separately consistently understates the joint risk position.
An integrated model typically uses Safran Risk, Primavera Risk Analysis or @Risk with integrated cost-schedule capability. Activities carry both duration and cost uncertainty; discrete risk events can impact either duration, cost, or both; and the simulation runs the network so that a delayed critical path automatically extends cost-loaded activities and adds the associated time-related cost. The output is a bivariate distribution showing the joint probability of different time and cost outcomes.
The practical value of an integrated model is that it produces a coherent confidence position. A sponsor asking "what is the P80 cost if we also need P80 confidence on time?" cannot be answered by running two separate models — the true joint P80 is higher than either individual P80 taken alone. AACE International Recommended Practice 57R-09 describes the method in detail. On UK infrastructure programmes where both time and cost confidence are governance-critical, integrated cost-schedule risk analysis is the standard for rigorous QRA work.
Used in practice
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Frequently asked
- What is QCSRA (Integrated Cost-Schedule Risk Analysis)?
- QCSRA — sometimes shortened to ICSRA or CSRA — is a Monte Carlo model that analyses schedule and cost risk together in a single integrated simulation. It captures the dependencies between the two: schedule slip drives prolongation cost (preliminaries, site overheads, liquidated damages) and cost pressure drives schedule compression. AACE International Recommended Practice 57R-09 describes the methodology.
- What is the difference between QCRA, QSRA and QCSRA?
- QCRA (Quantitative Cost Risk Analysis) models cost uncertainty alone — three-point estimates on cost lines plus discrete risk events with cost impact. QSRA (Quantitative Schedule Risk Analysis) models schedule uncertainty alone — three-point estimates on activity durations plus discrete risk events with schedule impact. QCSRA (Integrated Cost-Schedule Risk Analysis) combines both into a single model so the time-cost dependencies are captured explicitly. Two separate models consistently understate the joint risk position.
- Why use QCSRA instead of QCRA and QSRA separately?
- Schedule and cost risk are not independent. Extended programme duration drives time-related cost. Cost overruns drive schedule compression decisions that introduce their own risk. Running QCRA and QSRA as separate models loses these interactions. The true joint P80 (the cost AND schedule a sponsor can be 80% confident in) is higher than either individual P80 taken alone — and that's the number that matters for governance.
- What tools do QCSRA models run in?
- Safran Risk, Primavera Risk Analysis (formerly Pertmaster), @Risk, and Acumen Risk all support integrated cost-schedule modelling. Activities carry both duration and cost uncertainty; discrete risks can impact duration, cost, or both; and the simulation runs the network so delayed critical path activities automatically extend cost-loaded preliminaries. Tool choice depends on contract requirements (some clients specify Safran or PRA), team capability, and integration with the planning environment.
Related terms
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