plotAdjacent function

Plot category probabilities of adjacent category logit model

Function for plotting category probabilities function estimated by vglm() function from the VGAM package using the ggplot2 package.

plotAdjacent(x, matching.name = "matching")

Arguments

• x: object of class vglm
• matching.name: character: name of matching criterion used for estimation in x.

Returns

An object of class ggplot and/or gg.

Examples

# loading packages
library(VGAM)

# loading data
data(Science, package = "mirt")

# total score calculation
score <- rowSums(Science)
Science[, 1] <- factor(Science[, 1], levels = sort(unique(Science[, 1])), ordered = TRUE)

# adjacent category logit model for item 1
fit <- vglm(Science[, 1] ~ score, family = acat(reverse = FALSE, parallel = TRUE))
# coefficients for item 1
coef(fit)

plotAdjacent(fit, matching.name = "Total score")

See Also

VGAM::vglm()

Author(s)

Tomas Jurica

Institute of Computer Science of the Czech Academy of Sciences

Adela Hladka

Institute of Computer Science of the Czech Academy of Sciences

hladka@cs.cas.cz

Patricia Martinkova

Institute of Computer Science of the Czech Academy of Sciences

martinkova@cs.cas.cz