- Working years aafter the acquisition of a license and bin this hospital. cNurses were working under the 3-shift system so that their working h/day, no. of night duty/month, and working days/month were the same under both systems. dWorking days in another hospitals. Statistical differences were analyzed either by eone-way ANOVA followed by Scheffe test as a post hoc test or fStudent’s t test (*P < 0.05)