Translates a fitted item response model from the mirt package into a crossed-plate UMG: latent ability dimensions become latent continuous vertices in the person plate, the observed responses become an observed categorical vertex at the crossing of the person and item plates, and the item parameters become fixed-unknown diamonds in the item plate. The number of ability dimensions is read from the fitted object; the item-parameter glyphs are generic (discrimination and location), since the diagram represents the structure rather than per-item estimates.
Usage
umg_from_mirt(object, model = c("2PL", "1PL", "3PL", "graded"))Arguments
- object
A fitted
SingleGroupClass/mirtobject, or an integer giving the number of latent dimensions (for a quick structural sketch without a fit).- model
Item-model label deciding which item-parameter vertices to draw: one of
"2PL","1PL","3PL","graded". Whenobjectis a fitted mirt model andmodelis not supplied, the item type is read from the fitted object (Raschmaps to"1PL";graded,grsm,gpcm, andgpcmIRTmap to"graded"); an explicitmodelargument overrides the fit.