irtoys (version 0.1.4)

dpv: Draw plausible values

Description

Draws (by rejection sampling) plausible values from the posterior distribution of ability

Usage

dpv(resp, ip, mu=0, sigma=1, n=5)

Arguments

resp

A matrix of responses: persons as rows, items as columns, entries are either 0 or 1, no missing data

ip

Item parameters: a matrix with one row per item, and three columns: [,1] item discrimination $a$, [,2] item difficulty $b$, and [,3] asymptote $c$.

mu

Mean of the apriori distribution. Ignored when method="ML". Default is 0.

sigma

Standard deviation of the apriori distribution. Ignored when method="ML". Default is 1.

n

The number of plausible values to draw for each person (default is 5).

Value

• A matrix with n columns

See Also

mlebme, eap

Examples

data(Scored)
p.2pl <- est(Scored, model="2PL", engine="ltm")
plval <- dpv(resp=Scored, ip=p.2pl)