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Generalized partial credit model (alias of Gpcm)

Source: R/Irtgpc.R
Irtgpc.Rd

Muraki's GPCM is already implemented as Gpcm; this is the same estimator exported under the catalogue's second spelling and delegates to it rather than carrying a second copy.

Usage

Irtgpc(y, theta, a, b_j)

Arguments

y

Observed categories, 0-based, one per person.

theta

Person abilities, same length as y.

a

Item slope, positive.

b_j

Step parameters; their count sets the category count.

Value

As Gpcm.

References

Muraki (1992), A generalized partial credit model, Applied Psychological Measurement 16(2):159-176. doi:10.1177/014662169201600206

Examples

Irtgpc(c(0, 1, 2), theta = c(0, 0.5, -0.5), a = 1, b_j = c(-1, 0, 1))
#> $estimate
#> [1] 0.3172924
#> 
#> $p_observed
#> [1] 0.42231880 0.45186276 0.07769558
#> 
#> $probs_first
#> [1] 0.4223188 0.4223188 0.1553624
#> 
#> $loglik
#> [1] -4.211328
#> 
#> $categories
#> [1] 3
#> 
#> $n
#> [1] 3
#> 
#> $method
#> [1] "GPCM eq. (1) of Muraki (1992)"
#> 
#> attr(,"class")
#> [1] "morie_rich_result" "list"