Inter- and intra-examiner variability in scoring supragingival plaque: II. Statistical analysis.

Inter- and intra-examiner variability in scoring supragingival plaque using the Turesky modification of the Quigley-Hein method was analyzed for four examiners each examining 24 patients twice. There was no evidence of systematic differences between the dentists and dental hygienists or between the more experienced and less experienced examiners in their mean scores, in the variability of their scores, or in the precision of their scores. The major sources of extraneous variation in the scores were measurement error, inter-examiner variation (not accounted for by professional training or experience), and a failure of examiners to apply their scoring criteria uniformly to all patients.