mixor (version 1.0.4)

irt.data: Armed Servces Vocational Aptitude Battery

Description

Arithmetic reasoning items from the Armed Servces Vocational Aptitude Battery

Usage

data(irt.data)

Format

A data frame with 128 observations on the following 13 variables.

ID

a numeric vector indicating unique pattern identifier

Resp

item response (0 = incorrect; 1 = correct)

int

a numeric vector of ones; used in MIXOR stand-alone program to represent the intercept

Item1

Arithmetic reasoning item 1 (0 = no; 1 = yes)

Item2

Arithmetic reasoning item 2 (0 = no; 1 = yes)

Item3

Arithmetic reasoning item 3 (0 = no; 1 = yes)

Item4

Arithmetic reasoning item 4 (0 = no; 1 = yes)

SexF

an indicator variable representing gender (0 = female; 1 = male)

SexItem1

Gender by Item1 interaction

SexItem2

Gender by Item2 interaction

SexItem3

Gender by Item3 interaction

SexItem4

Gender by Item4 interaction

freq

frequency weight of pattern

References

Mislevy R.J. (1985) Estimation of latent group effects Journal of the American Statistical Association 80, 993-997.

Examples

# NOT RUN {
library("mixor")
data("irt.data")
## Sort data by ID
irt.data<-irt.data[order(irt.data$ID),]
# 2 parameter logistic IRT model
Fitted.irt<-mixor(Resp~Item1+Item2+Item3+Item4-1, data=irt.data, id=ID, 
     weights=freq, which.random.slope=1:4, link="logit", nAGQ=10, 
	 random.effect.mean=FALSE, UNID=1, vcov=FALSE)
summary(Fitted.irt)
# 2 parameter logistic IRT model with Sex interations on item parameters
Fitted.irt2<-mixor(Resp~Item1+Item2+Item3+Item4+SexItem1+SexItem2+SexItem3+SexItem4-1, 
     data=irt.data, id=ID, weights=freq, which.random.slope=1:8, link="logit", 
	 nAGQ=10, random.effect.mean=FALSE, UNID=1, vcov=FALSE)
summary(Fitted.irt2)
# }