xxIRT (version 2.0.1)

estimate_3pl: Estimate Both People and Item Parameters

Description

Estimates both people and item responses using MMLE and JMLE

Usage

estimate_3pl(responses, ...)

Arguments

responses

a data frame of responses

...

other optional arguments

Value

a 3PL model with estimated people and item parameters

Examples

# NOT RUN {
data <- irt_model("3pl")$gendata(2000, 50)
x <- estimate_3pl(data$responses, debug=TRUE)
cor(data$people$theta, x$people$theta)
plot(data$people$theta, x$people$theta, xlim=c(-4,4), ylim=c(-4,4), 
xlab="True", ylab="Est.", col=rgb(.8,.2,.2,.7))
cor(data$items, x$items)
plot(data$items$a, x$items$a, xlim=c(0,2), ylim=c(0,2), 
xlab="True", ylab="Est.", col=rgb(.8,.2,.2,.7))
plot(data$items$b, x$items$b, xlim=c(-3,3), ylim=c(-3,3), 
xlab="True", ylab="Est.", col=rgb(.8,.2,.2,.7))
plot(data$items$c, x$items$c, xlim=c(0,.4), ylim=c(0,.4), 
xlab="True", ylab="Est.", col=rgb(.8,.2,.2,.7))
# }