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Tips for Recognizing Rater Bias

Bias occurs when you allow your personal opinion of the employee to influence your decisions. Try to identify the cause or root of the bias and then address it. Common types of bias can be grouped into three broad categories:

  • Bias based on judgment of performance

  • Bias based on personal preference or style

  • Bias based on time factors.

Bias Based on Judgment of Performance
Type of Bias Description
Halo Effect

Overrating an employee in other areas because they are outstanding in one area of performance.
Horns Effect

Underrating an employee in all areas who does poorly in one area.
Contrast Effect

Evaluating employees in comparison with other employees rather than against the standards for the job.

Central Tendency Error

Attempting to treat all employees equally by rating everyone in the middle of the scale even if some performances clearly warrant a substantially higher or lower rating.
Rotating Rotating higher ratings to make everyone happy.

Negative and Positive Skew

The opposite of central tendency. Rating all individuals as higher or lower than their performance actually warrants.
Interpretation

Developing conclusions or making assumptions. Not based on facts but on the rater’s opinion of the facts.

Bias Based on Personal Preference or Style
Type of Bias Description
First Impression Error Making an initial positive or negative judgment of an employee and allowing that first impression to distort later interactions.

Similar-to-Me Effect

Rating an employee who resembles you higher than you rate other employees.
Attribution Bias

Attributing performance failings to factors under the employee’s control and performance successes to external causes.

Stereotyping

 Generalizing across groups and ignoring individual differences.
Bias Based on Time Factors
Type of Bias Description
Quick and Dirty Effect Giving all employees the same rating regardless of their performance in order to get the evaluations done quickly.
Recency Effect

Allowing events that happened recently to have more influence on the rating than events of many months ago.
Time Delay

Forgetting the details of performance over the rating period.


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