Statistical methodology
EVENTS
Data were collected and entered into the computer using Statistical Package for Social Science program for statistical analysis (ver 25). Data were described using median and interquartile range. Comparisons were carried out between two studied independent not-normally distributed subgroups using the Mann–Whitney U test. Comparisons were carried out among related samples by Friedman’s test. Odds ratio (OR) was used to quantify the strength of the association between two events. McNemar’s test was used on paired nominal data with matched pairs of subjects to determine whether the row and column marginal frequencies were equal. Statistical significance was tested at Based on El-Rashidy et al.’s