Non-parametric item banks

Non-parametric IRT models

Sampled and smoothed item banks

FittedItemBanks.DichotomousPointsItemBankType
struct DichotomousPointsItemBank{DomainT} <: PointsItemBank
  • xs::Any

  • ys::Matrix{Float64}

DomainType(::DichotomousPointsItemBank) = DiscreteIndexableDomain()
ResponseType(::DichotomousPointsItemBank) = BooleanResponse()

An item bank where all items have IRFs computed at a fixed grid across the latent/ability dimension specified as xs. The responses are stored in ys. In most cases this item banks will be coupled with a Smoother and wrapped in a DichotomousSmoothedItemBank.

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FittedItemBanks.DichotomousSmoothedItemBankType
struct DichotomousSmoothedItemBank{P<:PointsItemBank, S<:Smoother} <: AbstractItemBank
DichotomousSmoothedItemBank(item_bank::PointsItemBank, smoother::Smother)
DomainType(::DichotomousSmoothedItemBank) = OneDimContinuousDomain()
ResponseType(::DichotomousSmoothedItemBank) = BooleanResponse()
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FittedItemBanks.KernelSmootherType
struct KernelSmoother{FunctionT} <: Smoother
  • kernel::Any

  • bandwidths::Vector{Float64}

A smoother that uses a kernel to smooth the IRF. The bandwidths field stores the kernel bandwidth for each item.

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FittedItemBanks.MultiGridDichotomousPointsItemBankType
struct MultiGridDichotomousPointsItemBank <: PointsItemBank
  • xs::ArraysOfArrays.VectorOfVectors{Float64, Vector{Float64}, Vector{Int64}, Vector{Tuple{}}}

  • ys::ArraysOfArrays.VectorOfVectors{Float64, Vector{Float64}, Vector{Int64}, Vector{Tuple{}}}

An item bank where all items each IRF has been computed on a potentially distrinct grid across the latent/ability dimension specified as xs. The responses are stored in ys. In most cases this item banks will be coupled with a Smoother and wrapped in a DichotomousSmoothedItemBank.

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FittedItemBanks.gridifyMethod
gridify(item_bank, xs)

Converts a dichotomous item bank item_bank into a gridded item bank by evaluating the items at points xs.

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