3. Statistics
Statistical analyses were performed using the SPSS software version 24.
The variables were investigated using visual (histograms, probability
plots) and analytical methods (Kolmogorov-Smirnor/Shapiro-Wilk’s test)
to determine whether or not they are normally distributed. Descriptive
analyses were presented using means and standart deviations for normally
distributed variables, and using medians and interquartile range for the
non-normally distributed variables. Student’s t-test was used to compare
parameters which were normally distributed, and the correlation
coefficients and their significance were calculated using the Pearson
test. Mann-Whitney U test was used to compare paramaters which were
non-normally distributed, and the correlation coefficients and their
significance were calculated using the Spearman test. A 5% type-I error
level was used to infer statistical significance.