xxIRT (version 1.1.0)

prob: Common Computations

Description

prob computes probability for a gve IRT object.

info computes information for a gve IRT object.

likelihood computes likelihood for a gve IRT object.

Usage

prob(x, summary = NULL, fun = NULL)
info(x, summary = NULL, fun = NULL)
likelihood(x, summary = NULL, fun = NULL, log = FALSE)

Arguments

x

an IRT object

summary

the direction of summarizing results: 1 by row (over items) and 2 by column (over people)

fun

the summarizing function

log

TRUE to take logarithm of results

Value

a matrix or vector (when summarized) results

See Also

Other commons: gen.irt, irt

Other commons: gen.irt, irt

Other commons: gen.irt, irt

Examples

# probabilities
prob(gen.irt(10, 5))
# product of probabilities
prob(gen.irt(10, 5), summary=1, fun=prod)
# information
info(gen.irt(10, 5)) 
# add information over items
info(gen.irt(10, 5), summary=1, fun=sum) 
# add information over people
info(gen.irt(10, 5), summary=2, fun=sum)
# likelihood of response vectors
likelihood(gen.rsp(gen.irt(10, 5)), summary=1, fun=prod)
# log-likelihood of response vectors
likelihood(gen.rsp(gen.irt(10, 5)), summary=1, fun=sum, log=TRUE)