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Probability atoms in a loss distribution

A probability atom creates a jump in the cumulative loss distribution at a particular loss amount.

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Read the outcome mass

In the original model, loss 10 has probability 25%. The cumulative distribution rises from 70% below 10 to 95% at 10. That positive mass is an atom, not a continuous range of nearby loss amounts.

Keep the jump in the record

Boundary at loss 10
QuantityProbability
Loss strictly below 1070%
Loss equal to 1025%
Loss at or below 1095%

Include only the selected portion when needed

At 90% confidence, the exact worst-tail average uses 5% probability from loss 10 plus all 5% at loss 50. The economic loss remains 10 for the included boundary portion; only its inclusion weight changes.

Combine identical loss values consistently

Several mutually exclusive scenario records may produce the same loss. Adding their probabilities leaves the distribution unchanged. Splitting or merging those records should not change the quantile or expected-shortfall result.

Further references