Types

Item response models in the AbstractItemResponseModels.jl interface are represented by a single abstract type, ItemResponseModel. Every implementation of an item response model by a package author must inherit from ItemResponseModel.

AbstractItemResponseModels.ItemResponseModel Type

ItemResponseModel

An abstract type representing an item response theory model.

Each implementation T <: ItemResponseModel must define the following traits:

• response_type: A valid ResponseType

• person_dimensionality: The number of dimensions for the person parameters

• item_dimensionality: The number of dimensions for the item parameters

• estimation_type: A valid EstimationType

Additionally T <: ItemResponseModel must implement the following interface:

• irf: An item response function returning the probability that a person with given ability estimate will answer an item with a particular response.

• iif: An item information function returning the information of answering with a particular response on an item given an ability estimate.

• expected_score: An expected score function returning the expected score for one or multiple items, given an ability estimate.

• information: An information function returning the information of one or multiple items, given an ability estimate.

• fit: A function fitting an item response model of type T to observed data.

• get_item_locations: A function returning the item locations for a given item.

• get_person_locations: A function returning the person locations for a given person.

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