plotModelExp {conquestr}

plotExpected

Description

Creates a plot of an item- or test- expected score curve. If ability estimates are provided, both empirical and model curves are produced. Can optionally handle weights and groups as required. Note this is not for use with rout files. See the generic function plotRout for plotting rout files.

Usage

plotModelExp(
  items,
  range = c(-6, 6),
  by = 0.1,
  bins = NULL,
  abilities = NULL,
  weights = NULL,
  group = NULL,
  scale = FALSE
)

Arguments

items

a list of one or more matrices of item parameters. Used in producing model-implied curves.

range

Lower and upper bounds to plot over (defaults to c(-6, 6). Used in producing model-implied curves. For empirical curves a range is chosen given the min and max values in abilities.

by

Increment to calculate expectation along range. Used in producing model-implied curves.

bins

A double. Optional. How many equally sized bins should abilities be broken up into? Used in producing empirical curves. If not provided and abilities are provided, a suitable value is chosen given the length of abilities.

abilities

A vector of doubles. Optional.

weights

A vector of doubles. Optional.

group

A vector of type factor. Optional.

scale

A Boolean. Whether plot should be scaled such that the Y-axis ranges from 0 to 1.

Value

A ggplot2 object.

Examples

myItem <- matrix(
  c(
    0, 0, 0, 1,
    1, 1, 0, 1
  ),
  ncol = 4, byrow=TRUE
)
myPlot <- plotModelExp(list(myItem))