Practical use cases
- Sizing the exposure from a key-person, single-team or hard-to-replace dependency.
- Comparing the relative risk of different groups on a consistent basis.
- Prioritising mitigation — cross-training, succession or retention — where exposure is highest.
Calculator
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How it works
The formula is:
Concentration = At-risk headcount ÷ Total headcount × 100; Expected exposure = At-risk headcount × Probability of loss % ÷ 100
Concentration shows how much of the workforce sits in the at-risk group; expected exposure applies your probability estimate to that group to size the likely loss in people. Both are planning estimates, not predictions.
Worked example: With 12 of 150 people in a critical group and a 30% loss estimate: concentration = 12 ÷ 150 × 100 = 8%; expected exposure = 12 × 0.30 ≈ 3.6 people.
How to read the result
High concentration means a lot depends on a small group, so a single departure hurts more. High expected exposure means the likely loss is large in absolute terms. Read them together: a small but business-critical group with a high loss probability can outrank a larger group with low probability.
The probability is your own estimate, so treat exposure as a range and use it to prioritise mitigation — cross-training, documentation, succession and retention — rather than as a forecast of who will leave.
Common mistakes
- Counting more at-risk people than the total headcount, which makes concentration meaningless.
- Treating the probability estimate as a certainty.
- Looking at concentration or exposure alone instead of both together.
- Sizing the risk but never acting on the mitigation it points to.
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