Proper statistical analysis of transepidermal water loss (TEWL) measurements in bioengineering studies

In irritancy studies, measurement of transepidermal water loss (TEWL) is a widely used technique to assess barrier function. Using inappropriate statistical methods, however, leads to loss of information and misinterpretation of results. In this paper, we discuss some problems and pitfalls when using a suitable statistical technique for most designs in bioengineering studies, analysis of variance (ANOVA): multiple comparisons, choice of sample size and violation of statistical assumptions. For clarification of these points, a practical example will be given. Using the proposed adequate statistical methods correctly will, although accompanied by increased complexity, increase the efficiency of bioengineering studies.