Alpha level distortions with repeated testing of follow-up dental data

The statistical consequences of repeated significance testing of follow-up dental data were evaluated by computerized Monte Carlo simulation. Substantial distortions in nominal alpha level were noted, particularly when the scores for individual subjects were not highly correlated between statistical observations. Suggested methods of controlling this distortion include the pre-specification of a terminal statistical analysis that would be given best evidence status and the partitioning of alpha error among all analyses by Bonferroni's inequality.