In this Journal, Lewis and colleagues introduced a new Reliable Change Index (RCI(WSD)), which incorporated the within-subject standard deviation (WSD) of a repeated measurement design as the standard error. In this note, two opposite errors in using WSD this way are demonstrated. First, being the standard error of measurement of only a single assessment makes WSD too small when practice effect...

In most clinical and experimental studies, the standard deviation (SD) and the estimated standard error of the mean (SEM) are used to present the characteristics of sample data and to explain statistical analysis results. However, some authors occasionally muddle the distinctive usage between the SD and SEM in medical literature. Because the process of calculating the SD and SEM includes differ...

As a nonstatistician, I have watched the discussion on this topic with interest (1–8). Dr. Curren-Everett and others make a clear statement that variability of results should always be reported using the standard deviation (SD) and not the standard error (SE). Others cited above variously agree and disagree with the guidelines published by Dr. Curren-Everett and others. The reasoning provided i...

  Abstract   Background: Postural instability has been identified as a potential precursor of   falls in elderly subjects. Postural stability in quiet stance is commonly assessed with   center of pressure (COP) measures. The purpose of this study was to determine testretest reliability and minimal detectable change (MDC) for the center of pressure   (COP) measures in the elderly subjects.   Met...

In this paper a new Query Performance Prediction method is introduced. This method is based on the hypothesis that different score distributions appear for ‘hard’ and ‘easy’ queries. Following we propose a set of measures which try to capture the differences between both types of distributions, focusing on the dispersion degree among the scores. We have applied some variants of the classic stan...

Twenty ten-minute oral presentations made by Swedish students speaking English have been analyzed with respect to the standard deviation of F0 over long stretches of speech. Values have been normalized by division with the mean. Results show a strong correlation between proficiency in English and pitch variation for male speakers but not for females. The results also identify monotone and disfl...