profileplot {psychotools} | R Documentation |
Base graphics plotting function for profile plot visualization of IRT models.
profileplot(object, what = c("items", "thresholds", "discriminations"), parg = list(type = NULL, ref = NULL, alias = TRUE), index = TRUE, names = TRUE, main = NULL, abbreviate = FALSE, ref = TRUE, col = "lightgray", border = "black", pch = NULL, cex = 1, refcol = "lightgray", linecol = "black", lty = 2, ylim = NULL, xlab = NULL, ylab = NULL, add = FALSE, srt = 45, adj = c(1.1, 1.1), axes = TRUE, ...)
object |
a fitted model object of class |
what |
character, specifying the type of parameters to be plotted. |
parg |
list of arguments passed over to internal calls of
|
index |
logical, should different indexes for different items be used? |
names |
logical or character. If |
main |
character, specifying the overall title of the plot. |
abbreviate |
logical or numeric, specifying whether object names are to be abbreviated. If numeric this controls the length of the abbreviation. |
ref |
logical, whether to draw a horizontal line for the reference level.
Only takes effect if argument |
col, border, pch, cex |
Graphical appearance of plotting symbols. Can be of the same
length as the number of items, i.e., a different graphical appearance is used for
each item. If |
refcol |
character, specifying the line color for the reference line (if |
linecol |
character or numeric, specifying the line color to be used for the profiles. |
lty |
numeric, specifying the line type for the profiles. |
ylim |
numeric, specifying the y axis limits. |
xlab, ylab |
character, specifying the x and y axis labels. |
add |
logical. If |
srt, adj |
numeric. Angle ( |
axes |
logical. Should axes be drawn? |
... |
further arguments passed over to |
The profile plot visualization illustrates profiles of specific estimated parameters under a certain IRT model.
curveplot
, regionplot
,
infoplot
, piplot
## Load Verbal Aggression data data("VerbalAggression", package = "psychotools") ## Fit Rasch, rating scale and partial credit ## model to VerbalAggression data rmmod <- raschmodel(VerbalAggression$resp2) rsmod <- rsmodel(VerbalAggression$resp) pcmod <- pcmodel(VerbalAggression$resp) ## Profile plots of the item parameters of ## the three fitted IRT models plot(rmmod, type = "profile", what = "items", col = 4) plot(rsmod, type = "profile", what = "items", col = 2, add = TRUE) plot(pcmod, type = "profile", what = "items", col = 3, add = TRUE) legend(x = "topleft", legend = c("RM", "RSM", "PCM"), col = 1, bg = c(4, 2, 3), pch = 21, bty = "n") ## Profile plots of the threshold parameters of type 'mode' plot(rmmod, type = "profile", what = "thresholds", parg = list(type = "mode")) plot(rsmod, type = "profile", what = "thresholds", parg = list(type = "mode")) plot(pcmod, type = "profile", what = "thresholds", parg = list(type = "mode")) ## Profile plot of the discrimination parameters ## of a dichotomous Rasch model (all zero by definition) plot(rmmod, type = "profile", what = "discrimination")