Statistical Analysis
We calculated descriptive statistics to summarize our results. We
explored the normal distribution of the continuous variables with the
Shapiro-Wilk test. The results were express with mean and standard
deviation (SD) if we fail to reject a normal distribution. The results
were express with median and interquartile range (IQR) if normal
distribution was rejected. We calculated proportions and frequencies for
categorical variables. All the analyses were performed using the
software SPSS (IBM SPSS Statistics for Windows, Version 22.0. Armonk,
NY: IBM Corp). A Venn diagram was created with Eulerr web platform/site
to display the combination of the grading systems
(http://eulerr.co/).(16)