Tamara: Project risk analysis software for schedule and cost
Tamara runs Monte Carlo simulation on the Primavera P6 or Microsoft Project schedule you already have. It shows how likely you are to meet a completion date or a budget, how much contingency you need, and which tasks and risks drive the answer.
The date you can promise, and what drives it
A schedule gives one finish date, and it assumes every task goes to plan and no risk happens. Tamara gives the range instead: the chance of making the plan’s date, the date you can commit to with 80% confidence, the contingency that takes, and the tasks and risks behind it. Try it on Tamara’s demo schedule.
Try it: pick a date to promise
and see how many of the simulated futures make itWhich completion date can you promise?
The plan finishes on 25 December 2025. The example adds uncertainty to its tasks and the risks the project faces, and Tamara simulates the whole schedule. How likely is the plan’s date, and which date can the team commit to?
What the simulation shows: none of the simulated futures finishes by the plan’s date: the earliest is 12 January 2026. Half finish by 9 February 2026, and a date the team can promise with 80% confidence is 18 February 2026, 55 days after the plan. Tamara’s tornado chart then ranks the tasks those days come from.
What can Tamara do?
Tamara turns the schedule your planners already keep into a risk model, in eight steps from importing the plan to sending the reports. Each step has its own section below, most with a demo you can try.
What happens when you import a schedule into Tamara?
Tamara reads your schedule from Primavera P6, Microsoft Project or Microsoft Planner Premium, including nested and inter-connected projects, so the analysis starts from the real plan. While importing, it runs a Schedule Audit. This checks that the schedule is suitable for Monte Carlo simulation and scores its quality against goals you can edit.
- Your original file is never changed: Tamara works on its own copy.
- When the plan changes, one click updates the copy and keeps the risk data.
- Primavera custom fields come in too, for filtering and grouping results.
Illustrative audit of a 412-task Primavera P6 schedule. Green values meet the goal and red ones do not. You can edit every goal, and selecting a metric lists the tasks behind it.
Try it: pick a work amount level
Work Amount Uncertainty Definitions| Level | Less work | Most likely | More work |
|---|---|---|---|
| Low | -5% | 0% | +10% |
| Medium | -10% | 0% | +25% |
| High | -10% | 0% | +50% |
Example levels for a 20-day task. You name the levels and set the ranges.
Try it: pick a work amount level
Work Amount Uncertainty Definitions| Level | Less work | Most likely | More work |
|---|---|---|---|
| Low | -5% | 0% | +10% |
| Medium | -10% | 0% | +25% |
| High | -10% | 0% | +50% |
Example levels for a 20-day task. You name the levels and set the ranges.
Try it: pick a work amount level
Work Amount Uncertainty Definitions| Level | Less work | Most likely | More work |
|---|---|---|---|
| Low | -5% | 0% | +10% |
| Medium | -10% | 0% | +25% |
| High | -10% | 0% | +50% |
Example levels for a 20-day task. You name the levels and set the ranges.
How does Tamara describe uncertainty in durations and costs?
You do not type a three-point estimate into every task. You answer simple questions instead: how sure are we about the amount of work, how fast will this kind of work go, how firm is this cost or resource rate? Define a few levels once, give each task, cost or resource a level, and Tamara turns them into ranges.
- Work amount: how much work a task really holds.
- Productivity: one factor per work type moves every task of that type.
- Expenses: levels for the fixed and variable costs linked to tasks.
- Resources: uncertain cost rates for each resource group, multiplied by the simulated time each resource works.
What kinds of risk events can Tamara model?
Tamara models risk events separately from everyday uncertainty. Each has a chance or a frequency and a range of impact, and can be a threat or an opportunity. There are six kinds, including weather. We designed them with a dozen project risk and planning experts, from real cases on their own projects.
- One risk can hit several tasks, with a cost as well as a delay.
- Risks that can strike more than once, such as storms, take a frequency.
- Bring the risk register in from Pelican instead of re-typing it.
Try it: pick a kind of risk event
6 kindsA risk that delays one task: a late delivery, a repair, a contractor arriving late.
Equipment delivery late: 30% chance, 1 to 3 weeks. In this iteration it happens, and everything after the delivery moves.
How to model this in Tamara, on riskwiki →Try it: pick a kind of risk event
6 kindsOne risk on a set of identical tasks. Each task can be hit or missed on its own.
Equipment breakdown: 15% chance on each of the five units. Here it hits units 2 and 4.
How to model this in Tamara, on riskwiki →Try it: pick a kind of risk event
6 kindsA risk that changes how fast a type of work goes, so every task of that type stretches.
Night-work ban on the main-works contractor: 20% chance, its work 15 to 30% slower. Both main-works tasks stretch; the site works do not.
How to model this in Tamara, on riskwiki →Try it: pick a kind of risk event
6 kindsWork that may have to be added to the plan, such as a redesign. Also called probabilistic branching.
Design rejected at review: 20% chance of a 3-week redesign before the build.
How to model this in Tamara, on riskwiki →Try it: pick a kind of risk event
6 kindsAn event that stops all or part of the project for a while: a fire, an inspection, a spill. Every task running at the time is delayed.
Site shutdown after an incident: two weeks lost from week 8. Only the tasks running then stop; their successors move with them.
How to model this in Tamara, on riskwiki →Try it: pick a kind of risk event
6 kindsBad weather that stops exposed work for a while: storms, high winds, heavy rain or frost. Weather has its own risk type in Tamara, so you model it directly.
High winds stop lifting for two weeks from week 7. The outdoor installation is held up and the external works move with it; the indoor works carry on.
Same fence, two ways to model it
10 sections, each 3 to 6 days, most likely 4Each section is drawn on its own, so delays and early finishes cancel out. The total looks precise: the P80 is only 5 days above the 40-day estimate.
5,000 iterations.
Same fence, two ways to model it
10 sections, each 3 to 6 days, most likely 4One productivity factor for the fencing crew drives all ten sections. A slow crew is slow everywhere: the P80 is 49 days, 4 more than the independent version.
5,000 iterations.
How does Tamara handle correlation between tasks?
Tasks often share causes: the same contractor, the same weather, the same approvals. If a model treats them as independent, their delays cancel out and the finish date looks more certain than it is. Tamara asks for the shared causes instead of correlation coefficients, and the correlation follows from them.
- A risk linked to several tasks delays all of them, or none.
- A productivity factor shared by a work type moves all its tasks together.
- No correlation matrix to fill in, on schedules of any size.
How fast is Tamara?
Fast enough to run the master schedule itself, so there is no cut-down copy to maintain. Most real schedules have between 1,000 and 10,000 tasks. A 40,000-task schedule runs 10,000 iterations in under five minutes, and Tamara has been tested on real plans of up to 80,000 tasks.
- One run gives results for every task, summary and milestone.
- Set the number of iterations in Simulation Settings, from a quick check to a full analysis.
Where your schedule sits
Times measured by Vose Software on real project plans.
How do you read Tamara’s results?
Every task, summary and milestone gets results for its start, finish, duration and cost. Charts can show several scenarios at once, and the table beside each chart gives the date or cost at every confidence level. The tornado ranks what drives the result, and the stochastic Gantt shows each task’s likely dates.
- Read the P50 or P80 date straight from the statistics table.
- Trend charts show spend over time, and cost against finish date.
- Copy any chart or its data into Excel, Word or PowerPoint.
Cumulative
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Export SID
to ModelRisk
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Help
ModelRisk
PelicanCumulative
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Task-Specific
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FinishCumulative
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4 Weeks
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DescPeriodicFinish date of the whole project, with and without mitigation. The table reads the 80% line: 18 October 2027 Managed, 29 October 2027 Unmanaged. The planned date, 19 September 2027, is met in only 7% of Unmanaged iterations.
Illustrative project: nine tasks, four risks, 5,000 iterations. Managed adds the four mitigations from the next section.
Try it: build the Managed scenario
Expansion project, 5,000 iterationsTick the mitigations to include. Each lowers the chance of one risk and adds its cost to the budget.
No mitigations selected: this is the Unmanaged scenario.
Can Tamara compare risk management strategies?
Yes. A scenario can switch risks on or off, change their chance or impact, or change a productivity factor. Compare scenarios on one chart to find the mitigations that buy the most certainty for the money, and to show why the others are not worth it.
- Keep as many scenarios as you need, such as Unmanaged, Managed and Potential.
- Results charts and reports can show several scenarios at once.
How do you keep the analysis current?
A risk model that must be rebuilt at every schedule update gets done once and then forgotten. Tamara keeps the risk data attached to the schedule, so an update takes one click, and reports come from templates you design once. Getting from an updated schedule to reports in people’s inboxes can take as little as a minute.
Planners update the schedule in their scheduling tool as usual.
Tamara re-imports it and carries every risk and assignment across.
Run the simulation on the updated plan.
Each report is generated from its template as a PDF.
Report templates you design once
Results › Output › Report DesignerExample templates. Charts and statistics can also be copied into Word, PowerPoint or Excel.
Can Tamara model costs and calculations outside the schedule?
Yes. Not every cost sits in the master schedule, and not every risk fits a task. Tamara has a built-in spreadsheet with the ModelRisk modelling tools: 136 probability distributions, 34 time series models and 14 copulas. Use it to describe inputs in more detail, and to work out what the schedule result means for the business.
- Input spreadsheet: model durations, costs and risk sizes with any logic you need.
- Output spreadsheet: turn simulated dates and costs into delay damages, NPV or IRR.
- Export results as a SID file for a wider ModelRisk model in Excel.
What does Tamara work with?
Tamara sits between the scheduling tool your planners use and the places the results are needed: the risk register, the business case and the reports to the board. It reads Primavera P6, Microsoft Project and Microsoft Planner Premium schedules, exchanges risks and results with Pelican, and passes simulation results to ModelRisk models in Excel.
Pelican integration
Pull risks and mitigations from the Pelican risk register, and send each milestone’s likely cost and date back to its dashboards.
About Pelican →ModelRisk link
Save results as SID files for ModelRisk, to feed Excel models such as a business case.
About ModelRisk →Examples and help
Example models to start from, and help tutorials on good practice in schedule and cost risk analysis.
Moving from Primavera Risk Analysis
A step-by-step guide to rebuilding a PRA model in Tamara on your current P6 schedule.
Read the guide →Tamara features at a glance
Everything on this page is included in every Tamara licence. Download the Tamara brochure (PDF, 2.0 MB) ↓Download the one-page overview (PDF, 0.6 MB) ↓
Organisations that use Tamara
Tamara is made by Vose Software, the company behind ModelRisk and ModelChoice, which has built risk analysis software since 2008. Its co-founder, David Vose, wrote Risk Analysis: A Quantitative Guide.
One price, every feature
Tamara is sold as an annual licence with every feature. Time and volume discounts lower the price: work out your own quote with the price calculator. Network licences for teams are available too, and academic users have their own offer.
Tamara price calculatorFrequently asked questions
What is schedule risk analysis?
Schedule risk analysis, or QSRA, puts ranges and risk events on the tasks of a project schedule, then simulates the schedule thousands of times with Monte Carlo simulation. It shows how likely each finish date is, instead of the single date the plan gives, and which tasks and risks drive the delay. Our guide to Monte Carlo simulation in project management explains the method.
What is a P80 date?
A P80 date is a finish date the project has an 80% chance of meeting: in 80 of every 100 simulated futures the project finishes by then. Many owners and funders ask for a P50 date as the most likely outcome and a P80 or P90 date as the one to commit to. The gap between the plan’s date and the P80 date is the time contingency.
Why does the simulated finish come out later than the plan?
The plan uses one duration per task, usually the most likely one. Real durations tend to overrun by more than they underrun, a milestone that waits for several paths waits for the slowest one, and risk events that may happen are not in the plan at all. Each of these pushes the likely finish later.
Which scheduling tools does Tamara work with?
Tamara imports schedules from Primavera P6, Microsoft Project and Microsoft Planner Premium, including nested and inter-connected projects. It keeps its own copy, so the risk analysis starts from the real plan and is updated with one click when the plan changes.
Does Tamara analyse cost as well as time?
Yes. Tamara models the fixed and variable costs linked to tasks, uncertain resource rates multiplied by the time each resource works, and the cost of risk events, so a delay shows up in the budget too. It gives the total cost at any confidence level, cumulative cost over time, and a simulation spreadsheet for the economic effect of overruns.
Who on the project team uses Tamara?
Planners and schedulers, project controls, cost engineers and risk managers. Results go to sponsors and boards as charts and reports in PDF, Excel and Word, from report templates you design once and reuse.
Does Tamara change my Primavera P6 or Microsoft Project file?
No. Tamara keeps the risk model with its own copy of the imported schedule and never modifies the original file. When the plan changes, one click updates Tamara’s copy and carries the risk information across.
Can I build or edit a schedule in Tamara?
No. Tamara works from the schedule your planners maintain in Primavera P6 or Microsoft Project. Make logic changes there, then update Tamara in one click, so there is only ever one version of the plan.
Do I need to know statistics to use Tamara?
No. You describe uncertainty with levels you name yourself, and risks with a chance and a range of impact. Tamara comes with example models, and the help file has tutorials on good practice in schedule and cost risk analysis. The spreadsheet’s distributions are there when you need more detail.
What do I need to run Tamara?
Tamara is a 64-bit desktop application for Windows 10 and 11, built on .NET 8. It is licensed for a single computer or across a network. Full details are on the system requirements page.
Is there a free trial?
Yes. The 15-day trial is fully functional and imports your own P6 or Microsoft Project schedule, so you can run your first analysis on a project you are working on.
Run your own schedule through Tamara
Download the full product free for 15 days, import your P6 or Microsoft Project schedule and find the date you can promise.
Every feature at a glance ↑Download the Tamara brochure (PDF, 2.0 MB) ↓Download the one-page overview (PDF, 0.6 MB) ↓