2.4. Statistical Methods
Categorical data were presented in absolute and relative frequencies. Differences in categorical variables were tested by the McNemar–Bowker test or the marginal homogeneity test. The normality of the distribution of continuous variables was tested by Shapiro–Wilkinson test. Numerical data are described by median and interquartile range. Differences in numerical variables were tested by the Wilcoxon test. The association score is given by the Spearman correlation coefficient. All 