2.5 | Statistical analysis
All statistical tests were performed using the STATISTICA 13.0 software provided by StatSoft Inc. (Poland). The Kolmogorov-Smirnow test was used to determine the significance of differences in the distribution of the studied variables in relation to the normal distribution. The t-test was used for the comparison of means from the groups with a normal distribution, while for others the Mann-Whitney U test was used. For comparisons of multiple groups, the Bonferroni correction for the t-test and Kruskal-Wallis ANOVA rank test were used, respectively.
Categorical variables were presented as n (%) and compared with each other using the χ2 test. The control group and research subgroups were paired to test the null hypothesis that plasma PAF-AH activity is not related to the severity of the post-stinging reaction. The established level of statistical significance was α = 0.05.
The correlations between the variables were investigated by calculating the Spearman’s rank coefficient. It was considered significant when: r > 0.3 or r < -0.3.
A regression analysis was performed and the receiver operating characteristic (ROC) curve was laid out. Typical test parameters were calculated according to well-known definitions, such as sensitivity, specificity, accuracy, positive predictive value and negative predictive value [13].