Bell Curve in PMS is nothing but normalization process of employee performance / potential etc. Where ever performance appraisal is designed based on score / rank etc. the scores are represented with a digit such as 1/2/3/4/5 or A/B/C/D/E - where 1/A being Excellent / 2/B being Very Good / C/3 being Good / 4/D being Average / 5/E being below average.
Normally the rating vary depending upon the appraiser's experience and expertise to evaluate his / her subordinates. Those who do not wish to get into to controversy have a central tendency to mark/rate "Good" for all his subordinates. Few liberal bosses wishes to give all "Excellent", where as there are few stringent reporting officers wish to always wish to mark below "Good' for even good performers in his / her team.
Bell curve will help Reviewing officers to enforce to nromalise the ratings of all appraisals for a specific period and re-look at the ratings to push it under a Bell umbrella. As an organization, it is normal nature that, majority of the employees will fall under 'Good' Category - i.e. for the job we hire, is perfectly carry out the job. 'Average' peformers are the people who wish to be good but due to lack of some competencies, they are unable to achieve the good performance and not a bad element. These category of employees may require some feedback and time to develop to reach the level of a "Good" Performer. However, below average peformers are dangerous to the organization growth and they may be asked to look for a different job if not improved in the PIP period. (Performance Improvement Plan).
"Very Good" peformers are normally paid little more increment compare to 'Good' performers and also put them into fast track for future leadership roles.
During an appraisal period, certain weight age is given for personal contribution and those who add value and contribute to the growth of the organization and are in the "Very Good" Category are ranked as "Excellent".
Organizations will define the "Bell Rule" as to Left extreme of the Bell i.e. "Excellent" category will be max. 5 to0 8% of employees in any organization and similar 5 to 8% of employees fall on the right extreme of the "Bell" i.e "Below Average". Close to 60% of employees fall under 'Good" Category where as 15 to 18% will come under both 'Very Good" and "Average" on left and right of the centre part of the Bell.
Hope the above suffices / clarifies your doubt.
Guru
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