This function calculates Fleiss' Kappa.
fleiss_kappa(rater_one, rater_two, additional_raters = NULL)Retuns the value for Fleiss' Kappa.
factor rating of the first coder.
factor ratings of the second coder.
list Additional raters with same requirements as rater_one and rater_two. If
there are no additional raters set to NULL.
Fleiss, J. L. (1971). Measuring nominal scale agreement among many raters. Psychological Bulletin, 76(5), 378–382. doi:10.1037/h0031619
Other performance measures:
cohens_kappa(),
kendalls_w(),
kripp_alpha()