xxIRT (version 2.0.0)

estimate.3pl: Estimation of People and Item Parameters

Description

estimate.3pl estimates both people and item responses for given responses

Usage

estimate.3pl(responses, ...)

Arguments

responses

a data frame of responses

...

other optional arguments

Value

a 3PL irt.model object with estimated people and item parameters

Examples

## Not run: 
# data <- irt.model(model="3pl")$gen.data(2000, 50)
# x <- estimate.3pl(data$responses, debug=TRUE)
# cor(data$people$theta, people$theta)
# plot(data$people$theta, people$theta, xlim=c(-4,4), ylim=c(-4,4), 
# xlab="True", ylab="Est.", col=rgb(.8,.2,.2,.7))
# abline(a=0, b=1, lty=2)
# cor(data$items, items)
# plot(data$items$a, items$a, xlim=c(0,2), ylim=c(0,2), 
# xlab="True", ylab="Est.", col=rgb(.8,.2,.2,.7))
# abline(a=0, b=1, lty=2)
# plot(data$items$b, items$b, xlim=c(-3,3), ylim=c(-3,3), 
# xlab="True", ylab="Est.", col=rgb(.8,.2,.2,.7))
# abline(a=0, b=1, lty=2)
# plot(data$items$c, items$c, xlim=c(0,.4), ylim=c(0,.4), 
# xlab="True", ylab="Est.", col=rgb(.8,.2,.2,.7))
# abline(a=0, b=1, lty=2)
# ## End(Not run)