Glossary

This glossary hopes to definitively represent the tacit and explicit conventions applied in chainladder and its API.

General Terms

backend

• The storage of the numerical representation of a [Triangle]{.title-ref}. It can be ‘numpy’ for a dense CPU bound representation, ‘sparse’ for a sparse matrix CPU bound representation, or ‘cupy’ for a dense GPU bound representation.

estimator

• Any scikit-learn style class that can be fit to Triangle data.

hyperparameter

• An initial parameter of an estimator that can be set before the estimator is fit.

n_jobs

• The number of parallel jobs used by an estimator. A value of None uses a single processor unless overridden by a joblib parallel backend. A value of -1 uses all available processors.

predictor

• An estimator that has the predict method. All IBNR estimators of chainladder are predictors

transformer

• An estimator that has the transform method. The transform method returns instances of a Triangle. All estimators other than IBNR estimators are transformers.

Class API

Triangle

• The core data structure of the chainladder package. It emulates pandas’s functionality.

Development

• Transformers that produce, at a minimum, a multiplicative ldf_ property.

Tail

• Transformers that extends the Development estimator properties beyond the edge of a Triangle.

IBNR

• Predictors that produce, at a minimum, an ultimate_, ibnr_, full_expectation_ and full_triangle_ property.

Workflow

• Meta-estimators that allow for composition of other estimators.

Adjustments

• Estimators that allow for the adjustment of the values of a Triangle.

Triangle Concepts

axis

• Represents one of the four dimensions of a [Triangle]{.title-ref} instance. The four axes are index, columns, origin and development. valuation represents an additional axis implicit in the Triangle.

index

• The first axis of a 4D Triangle instance. Usually reserved for lines of business, or segments.

columns

• The second axis of a Triangle.

origin

• The third axis of a Triangle that represents origin dates of a Triangle.

development

• The fourth axis of a Triangle that represents either development age or valuation dates of a Triangle.

valuation

• An implicit axis representing the valuation period of each of the cells of a Triangle.