4.13. Statistical Analysis
The results of tested parameters were presented as the mean and standard deviation (SD). Statistical analyses were conducted using the Analysis Tool Excel of Microsoft 365 Apps for Enterprise (Microsoft Corporation, Redmond, WA, USA), Origin 2020 (OriginLab, Northampton, MA, USA) and R 2.13.1 (R Foundation for Statistical Computing, Vienna, Austria). The Anderson-Darling test was used for the analysis of normal distribution. The statistical significance of differences in parameters between the study phases within each respective group were analyzed with a one-sided paired t-test (differences normally distributed) or a one-sided paired Wilcoxon’s signed rank test (differences without normal distribution). The statistical significance of differences in parameters between the test group and placebo group were analyzed by either a two-sample t-test (normal distribution) or a Mann-Whitney U-test (non-normal distribution). Spearman correlation coefficients were calculated based on the changes of the washout period to both the intervention period after four and after eight weeks. Significant correlations were determined by means of t-test.