rpf (version 0.3)

sumScoreEAP: Compute the sum-score EAP table

Description

Observed tables cannot be computed when data is missing. Therefore, you can optionally omit items with the greatest number of responses missing when conducting the distribution test.

Usage

sumScoreEAP(grp, ..., qwidth = 6, qpoints = 49L, .twotier = TRUE)

Arguments

grp

a list with spec, param, mean, and cov

...

Not used. Forces remaining arguments to be specified by name.

qwidth

positive width of quadrature in Z units

qpoints

number of quadrature points

.twotier

whether to enable the two-tier optimization

Details

When two-tier covariance structure is detected, EAP scores are only reported for primary factors. It is possible to compute EAP scores for specific factors, but it is not clear why this would be useful because they are conditional on the specific factor sum scores. Moveover, the algorithm to compute them efficiently has not been published yet (as of Jun 2014).

Examples

# see Thissen, Pommerich, Billeaud, & Williams (1995, Table 2)
 spec <- list()
 spec[1:3] <- rpf.grm(outcomes=4)

 param <- matrix(c(1.87, .65, 1.97, 3.14,
                   2.66, .12, 1.57, 2.69,
                   1.24, .08, 2.03, 4.3), nrow=4)
 # fix parameterization
 param <- apply(param, 2, function(p) c(p[1], p[2:4] * -p[1]))

 grp <- list(spec=spec, mean=0, cov=matrix(1,1,1), param=param)
 sumScoreEAP(grp)