ICC {mokken}

Intraclass correlation

Description

Computes to intraclass correlation for multilevel data (ICC; Snijders & Bosker, 1999, p. 17) for each item and the total scale of a questionnaire (Koopman et al., in press) and the F-test for the null hypothesis that the (total scale) ICC is zero (Snijders & Bosker, 2012, p. 22)

Usage

    ICC(X)

Arguments

X

matrix or data frame of numeric data containing a grouping column and the item scores of nrow(X) respondents to ncol(X) - 1 items. Missing values are not allowed

Value

itemICC

The ICC per item

scaleICC

The ICC for the total scale and the corresponding results for the F-test

Author(s)

Letty Koopman [e-mail] L. Andries van der Ark [e-mail]

References

Koopman, L., Zijlstra, B. J. H., & Van der Ark, L. A. (in press). A two-step, test-guided Mokken scale analysis for nonclustered and clustered data. Quality of Life Research. (advanced online publication) doi:10.1007/s11136-021-02840-2

Snijders, T. A. B., & Bosker, R. J. (2012). Multilevel analysis: An introduction to basic and advanced multilevel modeling (2nd ed.). Sage.

See Also

SWMDK, MLcoefH,

Examples

# Data example (Koopman et al., 2020)
data(SWMDK)

# Compute ICC
ICC(SWMDK)