"congeneric.sim" <-
function(loads = c(0.8, 0.7, 0.6, 0.5),N = NULL, err=NULL, short=TRUE) {
n <- length(loads)
loading <- matrix(loads, nrow = n)
error <- diag(1, nrow = n)
if (!is.null(err)) {diag(error) <- err} else {
diag(error) <- sqrt(1 - loading^2) }
pattern <- cbind(loading, error)
colnames(pattern) <- c("theta", paste("e", seq(1:n), sep = ""))
rownames(pattern) <- c(paste("V", seq(1:n), sep = ""))
model <- pattern %*% t(pattern)
if(!is.null(N)) {latent <- matrix(rnorm(N * (n + 1)), ncol = (n + 1))
observed <- latent %*% t(pattern)
colnames(latent) <- c("theta", paste("e", seq(1:n), sep = ""))
if(short) model <- cor(observed) }
if (short) {return(model)} else {result <- list(model=model,pattern=pattern,r=cor(observed),latent=latent,observed=observed,N=N)
class(result) <- c("psych","sim")
return(result)}
}
"sim.congeneric" <-
function(loads = c(0.8, 0.7, 0.6, 0.5),N = NULL, err=NULL, short=TRUE,categorical=FALSE, low=-3,high=3,cuts=NULL) {
n <- length(loads)
loading <- matrix(loads, nrow = n)
error <- diag(1, nrow = n)
if (!is.null(err)) {diag(error) <- err} else {
diag(error) <- sqrt(1 - loading^2) }
pattern <- cbind(loading, error)
colnames(pattern) <- c("theta", paste("e", seq(1:n), sep = ""))
rownames(pattern) <- c(paste("V", seq(1:n), sep = ""))
model <- pattern %*% t(pattern)
if(!is.null(N)) {latent <- matrix(rnorm(N * (n + 1)), ncol = (n + 1))
observed <- latent %*% t(pattern)
if(is.null(cuts)) {
if (categorical) {
observed = round(observed) #round all items to nearest integer value
observed[(observed<= low)] <- low
observed[(observed>high) ] <- high
} } else {
temp <- observed
ncuts <- length(cuts)
temp[(observed<= cuts[1])] <- 1
if(ncuts > 1) {for (nc in 2:ncuts) {temp[(observed > cuts[nc-1]) & (observed <= cuts[nc])] <- nc}}
temp[(observed > cuts[ncuts])] <- ncuts+1
observed <- temp-1
}
colnames(latent) <- c("theta", paste("e", seq(1:n), sep = ""))
if(short) model <- cor(observed) }
if (short) {return(model)} else { if(!is.null(N)) {
result <- list(model=model,pattern=pattern,r=cor(observed),latent=latent,observed=observed,N=N) } else { result<- model}
class(result) <- c("psych","sim")
return(result)}
}
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