# draw_parameters: Draw plausible parameter instantiations from a given model In mirt: Multidimensional Item Response Theory

## Description

Draws plausible parameters from a model using parametric sampling (if the information matrix was computed) or via boostrap sampling. Primarily for use with the `DRF` function.

## Usage

 ```1 2 3 4 5 6 7``` ```draw_parameters( mod, draws, method = c("parametric", "boostrap"), redraws = 20, ... ) ```

## Arguments

 `mod` estimated single or multiple-group model `draws` number of draws to obtain `method` type of plausible values to obtain. Can be 'parametric', for the parametric sampling scheme which uses the estimated information matrix, or 'boostrap' to obtain values from the `boot` function. Default is 'parametric' `redraws` number of redraws to perform when the given parameteric sample does not satisfy the upper and lower parameter bounds. If a valid set cannot be found within this number of draws then an error will be thrown `...` additional arguments to be passed

## Value

returns a draws x p matrix of plausible parameters, where each row correspeonds to a single set

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25``` ```## Not run: set.seed(1234) n <- 40 N <- 500 # only first 5 items as anchors model <- 'F = 1-40 CONSTRAINB = (1-5, a1), (1-5, d)' a <- matrix(1, n) d <- matrix(rnorm(n), n) group <- c(rep('Group_1', N), rep('Group_2', N)) ## ------------- # groups completely equal dat1 <- simdata(a, d, N, itemtype = 'dich') dat2 <- simdata(a, d, N, itemtype = 'dich') dat <- rbind(dat1, dat2) mod <- multipleGroup(dat, model, group=group, SE=TRUE, invariance=c('free_means', 'free_var')) param_set <- draw_parameters(mod, 100) head(param_set) ## End(Not run) ```

mirt documentation built on June 29, 2021, 1:06 a.m.