plot fscores {ltm} | R Documentation |
Plots a Kernel Density Estimation of the distribution of the factor scores (i.e., person parameters). Provides also the option to include in the plot the item difficulty parameters (similar to the Item Person Maps).
## S3 method for class 'fscores': plot(x, bw = "nrd0", adjust = 2, kernel = "gaussian", include.items = FALSE, tol = 0.2, xlab = "Ability", ylab = "Density", main = "Kernel Density Estimation for Ability Estimates", pch = 16, cex = 1.5, ...)
x |
an object inheriting from class fscores . |
bw, adjust, kernel |
arguments to density() . |
include.items |
logical; if TRUE the item difficulty parameters are included in the plot. |
tol |
the tolerance used to group the item difficulty parameters, i.e., when include.items = TRUE
the values round(betas / tol) * tol are plotted, where beta is the numeric vector of
item difficulty parameters. |
xlab, ylab, main |
character string or an expression ; see title . |
pch, cex |
arguments to stripchart() ; used when include.items = TRUE . |
... |
extra graphical parameters to be passed to plot.density() . |
Dimitris Rizopoulos d.rizopoulos@erasmusmc.nl
## Factor Scores for LSAT data: fsc <- factor.scores(rasch(LSAT)) plot(fsc, include.items = TRUE, main = "KDE for Person Parameters") legend("left", "item parameters", pch = 16, cex = 1.5, bty = "n")