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Performance appraisal based on the Bell Curve method refers to pre-defined rankings that compare employee’s performance with respect to peers. Managers are expected to plot the performances of employees, along a distribution line, displaying each employee’s ranking distinctively.

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Appraisal - Pre-defined Distribution Curve fails always - McOxley

Performance appraisal based on the Bell Curve method refers to pre-defined rankings that compare employee’s performance with respect to peers. Managers are expected to plot the performances of employees, along a distribution line, displaying each employee’s ranking distinctively. Despite being a popular method of appraising employee performance, using Bell curves for performance reviews prove tricky and offer quite a few potential problems to watch for.

Normal Performance Appraisal Methods

Organizations the world over are using various options for measuring employee performance—assessment tests for ensuring skill sets, productivity metrics or ability to deliver accepted goals, the composite numbering system being a few. Companies using numeric scoring follow bell curve ranking—‘normal distribution’. This enables fixing the top and bottom performers, and identifies how a particular employee’s score deviates from the median score.

Role of Distribution Curve

One of the common practices of grading, using the Bell Curve does not really help in improving employee performance. In reality, it even makes performance and happiness of employees to drop. When Distribution Curve Method is adopted, care should be taken to see that appraisal should not be conducted on a group level with individual performance expectations. It should rather be the other way around.

Why Predefined Distribution Curve System Fails

Although carefully conducted performance appraisal reflects the capabilities and skills of individuals exactly, adopting the bell curve method may sometimes fail to mirror the ground reality due to following reasons:

  • Inaccuracy in assessment
  • It is not always necessary that some employees rank high while others low—in the case of strong teams with equally skilled members, managers in charge of ranking tend to place a few of them at the bottom or medium, to follow the law of the bell curve. So in high-performing teams, as someone has to be ranked low, may be wrongly placed in a worse ranking. On such occasions, Bell Curves are notorious to cause a higher employee turnover, increasing recruitment budget.

  • Collaboration & Team Spirit may get spoilt
  • As a group of employees involved in working together toward a common goal, a few of them scoring higher on the curve than the rest leads to loss of collaborative effort. Employees, when being compared with peers, feel at loss of face. Also, some employees have to fall under the low performance category irrespective of their performance, as others might have scored better.

  • Defiance & Resistance from Employees
  • Forced Ranking method, while raising the middle performers, ignores the efforts taken by under performers. The pre-defined Distribution Curve grades high performers, and low performers, forming 10% of the entire workforce, respectively. The rest of the team, a staggering 80% , make up the middle level. It leads to employee morality being damaged inadvertently.

""Distribution Curve System of performance appraisal follows a normal distribution, where a major portion of the employees will be average, with a few above and a few below. This may cause a situation where an employee, despite having met his goals, may not be rated better than others. Ranking using this method has to be handled cautiously, if employee dissatisfaction and revolt are to be avoided"

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