extract.group {mirt}

R Documentation

Extract a group from a multiple group mirt object

Description

Extract a single group from an object defined by multipleGroup.

Usage

extract.group(x, group)

Arguments

x	mirt model of class 'MultipleGroupClass'
group	the name of the group to extract

Author(s)

Phil Chalmers rphilip.chalmers@gmail.com

References

Chalmers, R., P. (2012). mirt: A Multidimensional Item Response Theory Package for the R Environment. Journal of Statistical Software, 48(6), 1-29. doi:10.18637/jss.v048.i06

See Also

extract.item, extract.mirt

Examples

## No test: 
set.seed(12345)
a <- matrix(abs(rnorm(15,1,.3)), ncol=1)
d <- matrix(rnorm(15,0,.7),ncol=1)
itemtype <- rep('2PL', nrow(a))
N <- 1000
dataset1 <- simdata(a, d, N, itemtype)
dataset2 <- simdata(a, d, N, itemtype, mu = .1, sigma = matrix(1.5))
dat <- rbind(dataset1, dataset2)
group <- c(rep('D1', N), rep('D2', N))
models <- 'F1 = 1-15'

mod_configural <- multipleGroup(dat, models, group = group)
group.1 <- extract.group(mod_configural, 'D1') #extract first group
summary(group.1)

##            F1     h2
## Item_1  0.532 0.2835
## Item_2  0.582 0.3383
## Item_3  0.487 0.2371
## Item_4  0.466 0.2176
## Item_5  0.542 0.2935
## Item_6  0.315 0.0992
## Item_7  0.599 0.3592
## Item_8  0.477 0.2280
## Item_9  0.464 0.2148
## Item_10 0.391 0.1529
## Item_11 0.438 0.1923
## Item_12 0.655 0.4291
## Item_13 0.604 0.3650
## Item_14 0.519 0.2699
## Item_15 0.453 0.2048
## 
## SS loadings:  3.885 
## Proportion Var:  0.259 
## 
## Factor correlations: 
## 
##    F1
## F1  1

plot(group.1)

## End(No test)

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