Slide 10 of 16
Notes:
These methods provide a relative measure of consistency and conformity. ICC depends upon the variance of the population suggests that the calculated values do not have an "exact" interpretation. The relative interpretation of a high ICC correlation is a somewhat superficial reason for the rational belief in the "equivalence" of the two methods.
Whitfield, J. W.: Intra-class rank correlation Biometrika 36:463-467 (1949)
Rothery, P.: A nonparametric measure of intraclass correlation Biometrika 66:629-639 (1979).
