Statistical Analysis
Descriptive statistics for socio-demographic and clinical characteristics are given in terms of mean and standard deviation for numerical variables and percentage distribution for categorical ones. The t-test or the corresponding non-parametric Mann–Whitney test (for non-Gaussian distributed variables) was used to compare differences of quantitative variables between two groups and to compare any differences within the experimental group attending biofeedback training. The magnitude of the effects is reported using Coehn’s d or standardized mean difference, for independent samples. In our analysis, 0.2 was considered a small effect, up to 0.5 a medium effect, and 0.8 or above a large effect. The Chi-square test was used to compare categorical variables between groups. We calculated the adjusted residuals (z-scores) and their associated p values to detect any positive (z > 1.96) and significant (p < 0.05) relationships between the variables. All tests were two-tailed and the probability of type I error was set at p < 0.05. All analyses were performed with SPSS 26.