CSPA key terms
CSPA · Get comfortable with the vocabulary.
- Exposure
A defined measure of insurance risk volume or time that must match the loss and claim-count population used in a rate.
- Claim frequency
The number of included claims per matching exposure unit, sensitive to how claims, dates, coverage, and exposure are defined.
- Claim severity
Average loss per included claim under specified coverage and expense definitions, distinguished from loss per policy or exposure.
- Pure premium
Loss cost per exposure, equal to compatible frequency times severity when the component definitions use the same population and basis.
- Loss development
Change from an earlier reported valuation toward a later or ultimate loss estimate, subject to the chosen data and development assumptions.
- Observational unit
The entity represented by a row, such as a policy-period, claim, or payment transaction, essential for valid joins and aggregation.
- Data leakage
Use of information in training or evaluation that would not legitimately be available under the intended prediction and validation design.
- Target encoding
A categorical transformation based on outcomes that requires careful training-only and out-of-fold construction to limit direct response leakage.
- Feature availability
The time at which a predictor would actually be accessible for scoring, which can differ from the event date recorded in a source.
- Sampling weight
A factor representing how observations contribute to a target population estimate when selection rates or other relevant sampling features differ.
- Link function
The specified transformation connecting a conditional response mean to a linear predictor, distinct from a transformation of each observed response.
- Offset
A known contribution with a specified coefficient in a linear predictor, often log exposure in an appropriately specified insurance count model.
- Odds
The ratio of event probability to its complement, a scale on which a logistic coefficient produces a multiplicative conditional effect.
- Interaction
A model term allowing the effect of one predictor to depend on another, requiring conditional interpretation of coefficients and mean ratios.
- Dispersion
A parameter or diagnostic concept describing variability relative to a specified mean-variance relationship, whose exact convention depends on the model family.
- Leaf prediction
A tree output for observations reaching a terminal region, computed according to the response, objective, and any supplied observation weights.
- Bagging
An ensemble approach that fits models to bootstrap resamples and combines their predictions, often reducing instability of flexible base learners.
- Gradient boosting
A sequential fitting approach that adds model contributions guided by an objective, with learning rate and model complexity affecting behavior.
- Permutation importance
A predictive importance measure based on performance change after disrupting a feature, sensitive to correlation and the evaluation design.
- Partial dependence
A summary of model predictions as selected features vary across a reference distribution, which may involve unrealistic correlated-feature combinations.
- Calibration
Agreement between predicted probabilities or means and observed outcomes at appropriate aggregate or conditional levels, distinct from ranking quality.
- ROC AUC
A binary discrimination measure interpretable through positive-negative score ranking with appropriate handling of ties, not a direct measure of probability accuracy.
- Precision
The fraction of predicted or selected positive cases that are truly positive under the specified threshold, population, and outcome definition.
- Recall
The fraction of actual positive cases selected as positive, dependent on the threshold and distinct from precision or the true-negative rate.
- Nested validation
An evaluation design separating model-selection procedures from outer performance estimation, intended to account for tuning as part of the fitted process.
- Decision utility
A stated measure of benefit and cost used to connect predictions with an action, requiring assumptions about capacity, consequences, and uncertainty.
- Prediction interval
An interval intended to describe variation of a future outcome under assumptions, rather than only uncertainty in an estimated conditional mean.
- Proxy variable
A field associated with another characteristic whose omission does not necessarily remove its information or resolve fairness and permitted-use concerns.
- Reproducible analysis
An analysis with sufficiently controlled data, code, transformations, splits, environment, and assumptions to explain and reconstruct its stated results.
- Model monitoring
A planned process for reviewing inputs, outputs, eventual outcomes, operational behavior, and response triggers with clear responsibility after deployment.