Scenarios and formulas
Listing the paths, reading the formula for each scenario.
A scenario is one specific path through the process. The expected value tells you the average; the scenarios tell you which cases that average is made of.
How scenarios are generated
- At an exclusive gateway: split into several scenarios, one per branch.
- At a parallel gateway: no split — every branch belongs to the same scenario, time takes the max, cost takes the sum.
- At a loop: unroll at most 2 visits per step (adjustable on the Units tab), then stop and mark the scenario as truncated.
With a loop, the number of scenarios is infinite. The scenario list is a tool for reading and understanding, so it has to be finite. The expected value, however, is not truncated — it is computed with an absorbing Markov chain, so it includes the full infinity of turns. The two numbers serve two different purposes.
What each scenario shows
| Element | Meaning |
|---|---|
| Time, cost | The total for that path alone |
| Probability | The product of the probabilities of the branches taken |
| Path | The chain of steps; a parallel block appears as ⇉ [A] ∥ [B] |
| Time formula | Each term added up, with MAX(...) for a parallel block |
| Cost formula | The same, with SUM(...) for a parallel block |
30 (Raise request) + 45 (Head of department approves) + 25 (Create PO) + 10 (Send PO)
+ MAX(120; 20) + 35 (Match documents) + 40 (Pay) = 305 minEvery term can be read and cross-checked against the step table, and MAX(120; 20) states clearly
which branch the parallel block took.
Total probability and coverage
The total probability across all scenarios tells you what percentage of the possibilities you have covered. Under 100% means the remainder falls into loop branches that were truncated. This number appears on the “Average across scenarios” card on the formulas tab.
Fastest and slowest
The first scenario in the list is the fastest, the last is the slowest — which is precisely the critical path. The distance between the two ends tells you whether your process is stable or erratic. If they differ by several times over, committing to a single deadline for a customer is a risky thing to do.
Exporting for further analysis
Export → Scenarios (.csv) gives you the full table: time, cost, probability, path and both formulas for every scenario — open it in Excel to build a chart or paste it into a report.