Displaying 1 result from an estimated 1 matches for "oneoverp".
2010 Nov 03
3
optim works on command-line but not inside a function
...lity
#of a positive outcome of an item with difficulty b,
#discriminativity a, in combination with a student with
#competence theta.
IRT.p <- function(theta, a, b){
epow <- exp(-a*(theta-b))
result <- 1/(1+epow)
result
}
# = IRT.p^-1 ; for usage in the loglikelihood
IRT.oneOverP <- function(theta, a, b){
epow <- exp(-a*(theta-b))
result <- (1+epow)
result
}
# = (1-IRT.p)^-1 ; for usage in the loglikelihood
IRT.oneOverPneg <- function(theta, a, b){
epow <- exp(a*(theta-b))
result <- (1+epow)
result
}
#simulation-based sample ge...