Why Bell curve method is important in performance appraisal methods ?

Bell curve method is used to rate performance of all those engaged in similar kind of tasks. It rates the subject work force relatively by indicating top and bottom (certain) percentage of performers and those in between. (for example top and bottom5% and remaining90%). Bell curve also identifies the mean performance index to rate the overall performance level of an org. The mean of bell curve can be used as an indicator to assess the effect of certain performance improvement measures such as trainings or use of latest technology.

It helps to improve the performance of employees.