*2.4. Statistical Analysis*

The appropriate sample size for this study was calculated via the online Surveymonkey® calculator. The population that was eligible for this study consisted of 2337 FPs that were registered in the Republic of Croatia at the current time. The calculator has shown that the collected sample, with the 95% confidence interval and 5% error margin, should be at least 331 FPs. We succeeded in fulfilling these criteria, and acquired an even larger sample for adding further power to this investigation.

The MedCalc statistical program (version 19.1.2., MedCalc Software, Ostend, Belgium) was used for statistical analysis of the results. Whole numbers and percentages were used for categorical data presentation, with chi-squared test and Fisher's exact test measuring statistical differences. D'Agostino–Pearson test was used for testing the normality of data distribution, and accordingly, continuous variables were presented as median and interquartile range, with Mann–Whitney U and Kruskall–Wallis test used to measure statistical differences. Furthermore, Spearman rank correlation coefficient was used to test the correlation between questionnaire scores and other relevant variables, while significant independent factors in association with burnout levels (according to total OBI score) and resilience (according to BRS score) were determined with multiple linear regression analysis. All the assumptions for using regression analysis were fulfilled, with enter selection algorithm used. Results were reported in the form of unstandardized beta coefficients (β), standard errors (SE), t values and *p*-values. Finally, in order to determine a relationship between selected independent variables and positive MHD history status in our participants, a multivariate logistic regression analysis with enter selection algorithm was used. The model was adjusted for age and gender, and inspected for the goodness of fit with the Hosmer Lemeshow test. Results were reported in the form of the adjusted odds ratios (OR), 95% confidence intervals and *p*-values. For this investigation, statistical significance was set at *p* < 0.05.

#### **3. Results**
