Analysis The agreement between electronic VAS and verbal NRS will be evaluated using Spearman rank correlation6 and Bland-Altman method. The Spearman coefficient will be presented together with 95% confident interval (CI). The Bland-Altman method involves plotting the mean of the electronic VAS and NRS against the difference between the 2 scores for each pair of data. Mean difference +/- standard deviation of the differences between electronic VAS and verbal NRS will be presented.