posterior: IRT Posterior Density
In wasabi1989/MiscPsycho: Miscellaneous Psychometric Analyses

Description Usage Arguments Author(s) Examples

Compute the density of theta

1	posterior(x, theta, params, ind.dichot, control = list())

`x`	A vector of observed item responses
`theta`	Ability estimate
`params`	Item parameters organized as a list of lists
`ind.dichot`	Indicator denoting which items in x are multiple choice
`control`	A list of control parameters, D A constant usually fixed at 1.7 to bring the logistic function into coincidence with the probit mu Mean of the prior distribution sigma Standard deviation of the prior distribution Q Number of quadrature points used in the Gauss-Hermite approximation

Harold C. Doran

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params <- list("3pl" = list(a = c(1,1), b = c(0, 1), c = c(0,0)),
               "gpcm" = list(a = c(1,1), d = list(item1 = c(0,1,2,3,4), item2 = c(0,.5,1, 1.5))))
posterior(x = c(0,1,2,2), theta = 1, params = params, ind.dichot=c(1,2))