Table 1:

Individual and group variability for the OKM grading scale

VariabilityStatistical Value
Individual
    InterobserverSubstantial agreementκ = 0.74 (P < .005)a
    IntraobserverAlmost perfect agreementκ = 0.99 (P < .005)a
Group
    Neuroradiology vs neurosurgeryNo significant difference in interpretationP = .329b
    Trainee vs attendingNo significant difference in interpretationP = .2b
  • a Generalized multirater κ calculated as described in Siegal and Castellan.3

  • b Significance determined using a Wilcoxon signed rank sum test.