| informationWrightMap {conquestr} | R Documentation |
Plots test information function, relative to ability density, and item locations.
informationWrightMap(
myItems,
myAbilities,
type = "empirical",
minTheta = NA,
maxTheta = NA,
stepTheta = NA,
scaleInfo = 1,
plotItemPoints = "deltadots"
)
myItems |
A list of matricies describing item parameters. |
myAbilities |
A vector of person abilities on one dimension. |
type |
A character String. Should the test information be calculated empirically ("empirical" - default) or analytically using moments of distribution ("approx"). |
minTheta |
The smallest value of ability PDF to plot. |
maxTheta |
The largest value of ability PDF to plot. |
stepTheta |
The increment to iterate over the ability PDF. Defaults to 0.01. |
scaleInfo |
A scaling factor to apply to the plot of tesr information. Because ability distribution is a PDF with area one, and a test information function has area L, this can make the plot more interpretable. Defaults to 1. |
plotItemPoints |
A character string indicating what item points should be plotted along the x-axis. similar to the histogram of item locations plotted on a Wrightmap. Can be "none", "deltadots", "thresholds". |
A ggplot2 object.
myDeltaDots <- data.frame(
id = c(1:10),
itemid = paste0("item", 1:10),
delta = rnorm(10)
)
MyTaus <- data.frame(
id = c(2L, 10L),
itemId = NA,
step = c(1L, 1L),
tau = rnorm(2)
)
myItemList <- makeItemList(deltaDot = myDeltaDots, tau = MyTaus)
myInfoPlot <- informationWrightMap(myItemList, rnorm(1000, 0, 1), minTheta=-5, maxTheta=5)