ItemResponsePlots.jl

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item_information_curve ​

# ItemResponsePlots.item_information_curve — Function.
julia
item_information_curve(model, item, response)
item_information_curve(model, item)

Create a plot of the item information curve for response of item.

If response is omitted, the default plot behaviour depends on model:

  • For models where response_type(model) == Dichotomous the total item information curve is plotted.

  • For models where response_type(model) <: Union{Nominal, Ordinal} all category information curves are plotted.

Plot attributes

Generic

  • color: The color of the item information curve.

  • uncertainty_color: The color of the displayed uncertainty information. For plots with uncertainty intervals this is the color of the confidence band. For plots with sample based uncertainty information this is the line color of the samples.

  • theta: The values of theta for which to plot the item information curve. default: -3.0:0.01:3.0.

Specific

Models with SamplingEstimate

  • samples: The number of samples to plot. default: 1000

  • uncertainty_type: Changes how the uncertainty of the estimate is displayed. If uncertainty_type = :samples, then iterations from the MCMC estimation are plotted. If unvertainty_type = :interval, then uncertainty intervals are plotted. default: :samples

  • quantiles: The lower and upper quantile for uncertainty intervals. default: (0.1, 0.9)

  • aggregate_fun: A function that aggregates MCMC samples. The provided function must take a vector as input and output a scalar value. If aggregate_fun = nothing no aggregate is plotted. default: mean

source


From ItemResponseFunctions.jl ​

Dichotomous items ​

julia
using CairoMakie
using ItemResponsePlots
using ItemResponseFunctions

item = (a = 2.17, b = 0.10, c = 0.05, d = 0.8, e = 2.33)

item_information_curve(FivePL, item)

julia
using CairoMakie
using ItemResponsePlots
using ItemResponseFunctions

item = (; b = 0.5)

item_information_curve(OnePL, item, 0)
item_information_curve!(OnePL, item, 1)

Polytomous items ​

julia
using CairoMakie
using ItemResponsePlots
using ItemResponseFunctions

item = (a = 1.43, b = 0.2, t = (-1.2, 0.2, 0.5, 0.9))

item_information_curve(GRSM, item)

axislegend(position = :lt)