Vose SoftwareModelRisk example · Pharmaceuticals and biotech
Clinical Trial Cost and Duration
What budget and what date for the top-line results? A Phase II trial's cost and timeline with contingency.
From the model’s saved run
The budget
P80 = the cost with an 80% chance of not being exceeded.
| Measure | Unit | Value |
|---|---|---|
| Base estimate (most likely values, no risks) | US$m | 12.77 |
| Mean total cost | US$m | 13.77 |
| Chance that the base estimate is enough | probability | 13.5% |
| P80 budget | US$m | 14.54 |
| Contingency for a P80 budget | US$m | 1.76 |
| Contingency as a share of the base estimate | 13.8% |
S-curve (cumulative probability) of Total cost from the saved simulation.
The business question
A biotech company is planning a Phase II trial of its lead compound at about 30 hospitals in Europe and the US. 180 patients must complete the 24 weeks of treatment. Some will drop out, and about a third of the patients screened will not meet the entry criteria.
The clinical team has given low, most likely and high estimates for each phase of the trial and each cost, and has listed three risks that would delay it: a protocol amendment, enrolment slow enough to need new sites, and a clinical hold by a regulator. Every month of delay costs the trial's running cost: the CRO's project management, monitoring and data management.
The protocol is approved in January 2027. The board wants a budget and a date for the top-line results.
- Who it is for
- Clinical operations and project managers, R&D finance, biotech management and boards.
- Main outputs
- Total cost and duration: mean, P50, P80, P90 · the base estimate's chance of being enough · contingency for a P80 budget and a P80 timeline · top-line results date at 50% and 80% confidence · what drives the cost.
How the model works
Three sheets after this one, read from left to right. Each one feeds the next.
Inputs sheet
The patients who must complete the trial, the dropout and screen-failure rates. Low, most likely and high estimates for each phase and each cost; the chance and the delay of each risk.
Trial sheet
The patients to enrol and to screen. The duration, phase by phase plus the risk delays, and the dates of first site open, last patient in and top-line results; the costs, including the running cost over the months the trial runs. The Base column repeats every row with the most likely values and no risks.
Results sheet
The cost and the duration at each confidence level. The chance that the base estimate is enough; the contingency for a P80 budget and a P80 timeline; the top-line results date; the inputs that drive the cost.
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The results in detail
The timeline
From the protocol's approval to the top-line results.
Histogram of Duration from the saved simulation.
| Measure | Unit | Value |
|---|---|---|
| Planned duration (most likely values, no risks) | months | 28.0 |
| Mean duration | months | 31.3 |
| Chance of finishing within the plan | probability | 12.5% |
| Duration with 80% confidence (P80) | months | 33.6 |
| Timeline contingency for 80% confidence | months | 5.6 |
| Top-line results on the plan | date | May 2029 |
| Top-line results with 50% confidence | date | Aug 2029 |
| Top-line results with 80% confidence | date | Oct 2029 |
Other confidence levels
Choose the confidence level, then read the budget and the duration.
| Measure | Unit | P50 | P80 | P90 | Mean |
|---|---|---|---|---|---|
| Total cost | US$m | 13.71 | 14.54 | 14.99 | 13.77 |
| Duration | months | 31.0 | 33.6 | 35.1 | 31.3 |
| Delay from the risks | months | 1.9 | 3.6 | 5.3 | 2.1 |
| Expected delay from the risks, calculated exactly (check) | months | 2.12 |
What drives the cost
Lowest and highest mean total cost over ten equal groups of each input (VoseSimSensitivityMean): estimate the top ones more carefully.
Tornado chart: the inputs ranked by how far the mean output moves across each input’s range.
The ranking as a table 13 inputs
| Input (ranked by influence) | Lowest mean | Highest mean | Rank |
|---|---|---|---|
| Cost per patient enrolled | 12.87 | 14.87 | 1 |
| Running cost per month | 13.14 | 14.46 | 2 |
| Clinical hold: delay | 13.71 | 14.77 | 3 |
| Enrolment period | 13.41 | 14.26 | 4 |
| Dropout rate | 13.40 | 14.22 | 5 |
| Slow enrolment: delay | 13.60 | 14.27 | 6 |
| Protocol amendment: delay | 13.62 | 14.11 | 7 |
| Drug supply and logistics | 13.61 | 14.05 | 8 |
| Set-up cost | 13.58 | 14.00 | 9 |
| Close-out period | 13.63 | 13.99 | 10 |
| Cost per patient screened | 13.63 | 13.99 | 11 |
| Screen-failure rate | 13.66 | 13.90 | 12 |
| Start-up period | 13.74 | 13.82 | 13 |
How to read these results
- The base estimate — every estimate at its most likely value, and no risks — is US$12.8 million and 28 months. It is enough only about one time in seven: most estimates can overrun by more than they can underrun, and the risks only ever add delay.
- A budget of about US$14.5 million has an 80% chance of being enough: a contingency of about US$1.8 million, 14% of the base estimate. The mean, about US$13.8 million, is what such trials cost on average.
- The top-line results are planned for May 2029, but August is as likely as not (50% confidence) and October gives 80% confidence: the timeline needs about 5.6 months of contingency. The three risks add about two months on average — 2.12 months calculated exactly, which checks the simulation — and a clinical hold, rare as it is, stretches the right tail.
- The cost per patient enrolled drives the cost most: negotiate it, or fix it per visit with the sites. Next come the running cost and whatever extends the trial — a clinical hold, a longer enrolment period, slow enrolment — because every month costs about US$180,000.
- Enrolment here is a single three-point estimate. PH-02 builds it from site openings and recruitment rates: the most common cause of delay in clinical trials.
See it move. Open the workbook, change an input on the Inputs sheet and run the simulation: every table and chart on this page updates in Excel.
Inputs and assumptions
Every assumption in the model, with its uncertainty and where it comes from. The figures are illustrative.
The trial 5 inputs
A Phase II trial at about 30 hospitals in Europe and the US.
| Assumption | Unit | Uncertainty | Low | Most likely | High |
|---|---|---|---|---|---|
| Patients who must complete the trialFrom the sample-size calculation: 90% power for the primary endpoint. | patients | Fixed | 180 | ||
| Dropout ratePatients who leave before the primary endpoint; 12–20% in similar trials. | of patients enrolled | PERT | 10% | 15% | 25% |
| Screen-failure ratePatients screened who do not meet the entry criteria. | of patients screened | PERT | 25% | 35% | 50% |
| Protocol approvedThe clock starts here. | date | Fixed | 4 Jan 2027 | ||
| Average days per monthTurns months into calendar days for the dates. | days | Calculated | 30.44 | ||
Duration 4 inputs
Back-to-back phases, in months.
| Assumption | Unit | Uncertainty | Low | Most likely | High |
|---|---|---|---|---|---|
| Start-up: approvals, contracts, first site openEthics committees and regulators in six countries. | months | PERT | 4.0 | 6.0 | 10.0 |
| Enrolment: first to last patient inThe clinical team's estimate for 30 sites. | months | PERT | 10.0 | 12.0 | 18.0 |
| Treatment of the last patient24 weeks, set by the protocol. | months | Fixed | 6 | ||
| Close-out: database lock to top-line results | months | PERT | 3.0 | 4.0 | 6.0 |
Costs 5 inputs
| Assumption | Unit | Uncertainty | Low | Most likely | High |
|---|---|---|---|---|---|
| Set-up: protocol, CRO start-up, approvals | US$m | PERT | 0.60 | 0.80 | 1.20 |
| Cost per patient screenedScreening visit and tests. | US$k | PERT | 1.5 | 2.0 | 3.0 |
| Cost per patient enrolledVisits, procedures, imaging, investigator fees. | US$k | PERT | 25.0 | 30.0 | 40.0 |
| Drug supply and logisticsManufacture, packaging, comparator, distribution. | US$m | PERT | 0.80 | 1.00 | 1.50 |
| Running cost per monthCRO management, monitoring, data management: from the first site open to the top-line results. | US$k / month | PERT | 150 | 180 | 230 |
Risks 6 inputs
Each risk delays the trial; its cost is the running cost of the months lost.
| Assumption | Unit | Uncertainty | Low | Most likely | High |
|---|---|---|---|---|---|
| Protocol amendment: chanceMost Phase II protocols are amended at least once. | probability | Fixed | 40% | ||
| Protocol amendment: delayRe-approval by ethics committees; sites retrained. | months | Risk event · PERT | 1.0 | 2.0 | 4.0 |
| Slow enrolment, new sites needed: chance | probability | Fixed | 30% | ||
| Slow enrolment: delayTime to open new sites. | months | Risk event · PERT | 2.0 | 3.0 | 5.0 |
| Clinical hold by a regulator: chanceA safety signal stops dosing until it is resolved. | probability | Fixed | 5% | ||
| Clinical hold: delay | months | Risk event · PERT | 3.0 | 6.0 | 9.0 |
Units and conventions
- Money
- US$ million (US$m); costs per patient in US$ thousand (US$k); today's prices.
- Time
- Months from the protocol's approval; dates at an average month of 30.4 days.
- P80
- The value with an 80% chance of not being exceeded.
- Base estimate
- Every estimate at its most likely value, and no risks.
Key assumptions and limitations
- Phases
- Back to back: start-up, enrolment, treatment of the last patient, close-out.
- Risks
- Independent; each adds its delay to the enrolment period, and the running cost continues while it lasts.
- Estimates
- Independent of each other; enrolment time does not depend on the number of patients (see PH-02 for a recruitment model).
- Data
- The company, the compound and all figures are invented for this example.
How to use it
- Enter your trial's size and the low, most likely and high estimates of your clinical team on the Inputs sheet.
- List the risks that would delay the trial, with their chance and their delay.
- Run a simulation from the ModelRisk ribbon (10,000 samples with a fixed seed are set).
- Set the budget and the timeline at the confidence level the board wants, and work on the top drivers.
The tornado chart fills in after a simulation with ModelRisk’s classic engine.
ModelRisk functions used
- VosePERT
- Three-point estimates of the phases, the costs and the dropout and screen-failure rates.
- VoseRiskEvent, VosePERTObject
- Each risk's delay: zero, or a PERT delay with the risk's chance.
- VoseInput, VoseOutput
- Mark the uncertain inputs for the tornado, and the outputs recorded at every sample.
- VoseSimMean, VoseSimPercentile, VoseSimProbability
- Statistics of the simulation on the Results sheet.
- VoseSimSensitivityMean
- The tornado chart: every VoseInput ranked by how far the mean total cost moves across its range.
Further reading
- How to calculate cost contingency (Vose guide)
- Sensitivity analysis in Excel: a tornado chart step by step (Vose guide)
- Sertkaya, A. et al. (2016). Key cost drivers of pharmaceutical clinical trials in the United States. Clinical Trials 13(2), 117–126.
- Vose, D. (2008). Risk Analysis: A Quantitative Guide, 3rd edition. Wiley — project risk analysis.
Download the workbook and run it yourself. It opens in Excel with ModelRisk. The free trial runs every example model.
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An illustrative example: the figures are invented for teaching and do not describe a real company, project or asset. Last updated 9 October 2026.