Reliability of shade selection using an intraoral spectrophotometer: common mistakes in reliability analysis

Excerpt

We were interested to read the paper by Witkowski S and colleagues published in the June 2012 issue of Clinical Oral Investigations. The authors’ aim was to evaluate the accuracy and reproducibility of human tooth shade selection using a digital spectrophotometer. They report the mean colour difference from the mean metric for measurement precision (reliability)! Also, least square test was used to assess inter- and intra-observer reliability [1]. Why did the authors not use well-known statistical tests for reliability analysis such as intra-class correlation coefficient for quantitative variables, weighted kappa for qualitative ones [2‐5] or other methods such as coefficient of variance for repeatability [2‐5], considering that the mean of the variables and using paired t test, least square test or correlation coefficient (r) are among the common mistakes in reliability analysis [2‐5]? Regarding reliability or agreement, it is good to know that not only avoiding common mistakes in reliability analysis but also taking into account clinical importance instead of statistical significance is a crucial issue in clinical reliability researches [2‐5]. …