"item.dichot" <-
function (nvar = 72, nsub = 500, circum = FALSE, xloading = 0.6,
yloading = 0.6, gloading = 0, xbias = 0, ybias = 0,
low = 0, high = 0)
{
avloading <- (xloading + yloading)/2
errorweight <- sqrt(1 - (avloading^2 + gloading^2))
g <- rnorm(nsub)
truex <- rnorm(nsub) * xloading + xbias
truey <- rnorm(nsub) * yloading + ybias
if (circum) {
radia <- seq(0, 2 * pi, len = nvar + 1)
rad <- radia[which(radia < 2 * pi)]
}
else rad <- c(rep(0, nvar/4), rep(pi/2, nvar/4), rep(pi,
nvar/4), rep(3 * pi/2, nvar/4))
error <- matrix(rnorm(nsub * (nvar)), nsub)
trueitem <- outer(truex, cos(rad)) + outer(truey, sin(rad))
item <- gloading * g + trueitem + errorweight * error
nvar2 <- nvar/2
iteml <- (item[,(1:nvar2)*2 -1] >= low)
itemh <- (item[,(1:nvar2)*2] >= high)
item <- cbind(iteml,itemh)+0
return(item)
}
#revised October 2 to make difficulty and direction of factor loading unconfounded
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