title: Accuracy of repeated single versus averages of repeated duplicates of probing depth measurements.
abstract: The present study aims to determine to which extent averages or deepest recordings of repeated duplicates of probing depth measurements may increase the accuracy as compared to repeated single measurements. In total, 1247 sites were recorded in 8 patients with advanced periodontitis. The patients had received initial treatment. Each site was probed 4 times with time intervals of 100 min. The standard deviation of differences between repeated single measurements of 0.97 mm decreased with a factor square root of 2 to 0.69 mm for differences between averages of repeated duplicates of measurements. Differences between the averages and the deepest recordings of repeated duplicates of measurements showed a non-Gaussian distribution. This implies that the type-I error can not be computed on the basis of the standard deviation of the error with the use of parametric statistical analysis. The best estimate for the type-I error is the observed frequency of differences. The type-I error for differences of 3 mm or more between repeated single measurements decreased from 1.5% to 0.9% and 0.2%, when deepest recordings and averages of repeated duplicates of measurements, respectively, were compared.
authors.affiliation: Department of Biomaterials, ACTA, Free University of Amsterdam, The Netherlands.
authors.forename: P T
authors.initials: PT
authors.lastname: Janssen
authors.forename: A
authors.initials: A
authors.lastname: Drayer
authors.forename: J A
authors.initials: JA
authors.lastname: Faber
authors.forename: W H
authors.initials: WH
authors.lastname: van Palenstein Helderman
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D010514:Periodontal Pocket / Q000175:diagnosis / Q000473:pathology*; D010517:Periodontics / Q000295:instrumentation; D010518:Periodontitis / Q000473:pathology*; D011336:Probability