Non-normality of distribution of Glasgow Coma Scores and Revised Trauma Scores.

STUDY
OBJECTIVE: Inferential and descriptive statistics continue to be used incorrectly when analyzing biomedical data. Glasgow Coma Score (GCS) and Revised Trauma Score (RTS) data have recently been described and analyzed using parametric statistical methods in several studies despite the ordinal nature of these data scales. The objective of this study was to determine whether GCS and RTS data are normally distributed, despite their ordinal nature. HYPOTHESIS: Neither GCS nor RTS data are normally distributed.
DESIGN: A retrospective review of GCS and RTS data obtained at a medical school teaching and county hospital that is a Level I trauma center. PARTICIPANTS: Patients who met criteria for trauma team activation at the hospital.
METHODS: GCS and RTS data distributions were compared to a standard normal distribution using the chi 2 goodness of fit test.
RESULTS: GCS and RTS data distributions differed significantly from the normal distribution for all data sets examined.
CONCLUSION: Parametric statistical descriptors and inferential methods are inappropriate for use with GCS and RTS data. Ordinal data should be tested for normality before statistical analysis with parametric statistical methods.