Harris hip pain scores, measured on a four point ordinal score scale, post-surgery for 58 patients at three occasions.
A data frame with 174 observations on the following four variables.
a patient identifier variable.
a factor with levels
recorded at baseline (1), two years (2) and five years (5) post-surgery.
a pain score coded as none (1), slight (2), mild (3) and moderate or marked (4).