2.5 Statistical analysis
Nominal variables are presented as absolute and relative (%) frequencies. Continuous variables are presented in violin plots to show frequency distribution, with median and quartiles. Data was evaluated for significant statistical differences using i) the Chi-square test to evaluate associations between two nominal variables, ii) the non-parametric Kruskal-Wallis test for multiple comparisons and iii) the non-parametric Mann-Whitney test for independent sample tests (Prism 8.0 for macOS; GraphPad Software, San Diego, CA, USA). Correlation was assessed with the Spearman method. A local regression fitting line was added to the scatter plot with a confidence level of 95%. Statistical significance was set at p < 0.05 (* p < 0.05; ** p < 0.01; *** p < 0.001; **** p < 0.0001).
Results