Glossary#

This glossary hopes to definitively represent the tacit and explicit conventions applied in chanladder 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.

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.