Intraclass correlation coefficients (ICC)

The six McGraw & Wong (1996) intraclass correlation coefficients from a subjects-by-raters (or subjects-by-repeated-measurements) matrix: ICC1, ICC2, ICC3 (single measurement) and ICC1k, ICC2k, ICC3k (average of k measurements). The standard index of test-retest / inter-rater reliability, computed from a two-way ANOVA. Reproduces the psych package (psych::ICC(lmer = FALSE)) to machine precision and pingouin.intraclass_corr bit-for-bit.

Usage

intraclassCorrelation(x)

Arguments

x

A subjects-by-raters numeric matrix (rows = targets/subjects, columns = raters or repeated measurements). Rows with any missing value are dropped.

Value

A data frame with one row per ICC form (form, ICC), carrying n (subjects) and k (raters/measurements) as attributes.

Examples

m <- matrix(rnorm(30), ncol = 3) + rnorm(10)
intraclassCorrelation(m)
#>    form       ICC
#> 1  ICC1 0.6073458
#> 2  ICC2 0.6028622
#> 3  ICC3 0.5828942
#> 4 ICC1k 0.8227048
#> 5 ICC2k 0.8199513
#> 6 ICC3k 0.8074116