rpf (version 0.5)

rpf.drm: Create a dichotomous response model

Description

For slope vector a, intercept c, pseudo-guessing parameter g, upper bound u, and latent ability vector theta, the response probability function is $$\mathrm P(\mathrm{pick}=0|a,c,g,u,\theta) = 1- \mathrm P(\mathrm{pick}=1|a,c,g,u,\theta)$$ $$\mathrm P(\mathrm{pick}=1|a,c,g,u,\theta) = g+(u-g)\frac{1}{1+\exp(-(a\theta + c))}$$

Usage

rpf.drm(factors = 1, multidimensional = TRUE, poor = FALSE)

Arguments

factors

the number of factors

multidimensional

whether to use a multidimensional model. Defaults to TRUE.

poor

if TRUE, use the traditional parameterization of the 1d model instead of the slope-intercept parameterization

Value

• an item model

Details

The pseudo-guessing and upper bound parameter are specified in logit units (see logit).

For discussion on the choice of priors see Cai, Yang, and Hansen (2011, p. 246).

References

Cai, L., Yang, J. S., & Hansen, M. (2011). Generalized Full-Information Item Bifactor Analysis. Psychological Methods, 16(3), 221-248.

Examples

spec <- rpf.drm()
rpf.prob(spec, rpf.rparam(spec), 0)