Estimates of reliability are often determined by the
value of the data obtained. With nominal data such
as agreement, the kappa statistic may be utilized.
Range of motion measurements using goniometry
and inclinometry collect ratio level data and the
reliability is most often calculated through the use of the Pearson’s (r) or intraclass correlation coefficient
(ICC). The Pearson’s correlation coefficient (r)is
typically used when the investigator is trying to
determine if a relationship exists between two
measurements or instruments.