Simulation of a Dirichlet Distributed Vectors
This function makes random draws from a Dirichlet distribution.
dirichlet.simul(alpha)
alpha |
A matrix with \bold{α} parameters of the Dirichlet distribution |
A data frame with Dirichlet distributed responses
############################################################################# # EXAMPLE 1: Simulation with two components ############################################################################# set.seed(789) N <- 2000 probs <- c(.7, .3) # define (extremal) class probabilities #*** alpha0=.2 -> nearly crisp latent classes alpha0 <- .2 alpha <- alpha0*probs alpha <- matrix( alpha, nrow=N, ncol=length(alpha), byrow=TRUE ) x <- sirt::dirichlet.simul( alpha ) htitle <- expression(paste( alpha[0], "=.2, ", p[1], "=.7" ) ) hist( x[,1], breaks=seq(0,1,len=20), main=htitle) #*** alpha0=3 -> strong deviation from crisp membership alpha0 <- 3 alpha <- alpha0*probs alpha <- matrix( alpha, nrow=N, ncol=length(alpha), byrow=TRUE ) x <- sirt::dirichlet.simul( alpha ) htitle <- expression(paste( alpha[0], "=3, ", p[1], "=.7" ) ) hist( x[,1], breaks=seq(0,1,len=20), main=htitle) ## Not run: ############################################################################# # EXAMPLE 2: Simulation with three components ############################################################################# set.seed(986) N <- 2000 probs <- c( .5, .35, .15 ) #*** alpha0=.2 alpha0 <- .2 alpha <- alpha0*probs alpha <- matrix( alpha, nrow=N, ncol=length(alpha), byrow=TRUE ) x <- sirt::dirichlet.simul( alpha ) htitle <- expression(paste( alpha[0], "=.2, ", p[1], "=.7" ) ) miceadds::library_install("ade4") ade4::triangle.plot(x, label=NULL, clabel=1) #*** alpha0=3 alpha0 <- 3 alpha <- alpha0*probs alpha <- matrix( alpha, nrow=N, ncol=length(alpha), byrow=TRUE ) x <- sirt::dirichlet.simul( alpha ) htitle <- expression(paste( alpha[0], "=3, ", p[1], "=.7" ) ) ade4::triangle.plot(x, label=NULL, clabel=1) ## End(Not run)
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