title: Reliability of caries data in three clinical trials.
abstract: The reliability of caries data obtained during three clinical trials is presented. Each of the three trials, conducted by different examiners, lasted 3 years and involved children aged 12 to 15 years. Reliability was quantified in terms of reliability coefficient and error variance, which allowed the effect of error upon the efficiency of each study to be measured. Reliability tended to be reduced when precaviation (initial) lesions were included in the DMFS count, but there was little difference between the reliability coefficients for each of four different surface-types. Error was more important in 3-year incremental rather than prevalence data, but nevertheless had a rather small influence upon sample size estimation or confidence limits of percent caries reductions.
mesh_terms: D000293:Adolescent; D002648:Child; D004245:DMF Index; D003731:Dental Caries / Q000175:diagnosis*; D005500:Follow-Up Studies; D006801:Humans; D013223:Statistics as Topic