What Is Rater Bias?

May We Recommend...

It's well known, from the social sciences, that when people evaluate something or someone, their evaluations reflect the thing or person being assessed, AND, the evaluator's built in biases. As human beings our judgements about many things are affected by our own perceptual googles. The effects of evaluator perceptions introduces highly subjective factors that make many evaluations more or less inaccurate.

How does this relate to performance appraisal? Bias becomes a bigger and bigger factor to the extent that the criteria for evaluation become more vague, general, and abstract. For example, if a criterion says "Sells one million dollars in homes", bias is less likely to invalidate the evaluation using that criterion, since the criterion is objective and measurable. However, if the criterion is "Sells a whoe bunch of houses", then the evaluation using this criterion is likely to be influenced by various biases, because it's much vaguer.

Rater bias is a major problem when managers rate employees using scales that are vague, or highly subjective, so if you use rating scales, it's likely that biases come into play.

Biases can work to inflate employee ratings, or to deflate them. And, the effects are largely unpredictable, since different managers will apply different biases. Sometimes the same manager will exhibit different rater biases across different employees.

Managers will do well to be aware of their possible evaluation biases, so they can try to eliminate them. And, of course, the more objective, measurable, and precise the criteria used, the less likely bias will contaminate employee ratings. However, it's true that biases are simply a built in hazard of using rating systems, and cannot be totally eliminated.

For an outline of specific biases, go back to the ranking and ratings main page.



About Company

Bacal & Associates was founded in 1992 by consultant and book author, Robert Bacal. Robert's books on performance management and reviews have been published by McGraw-Hill. He is available for consultation, training and keynote speaking on performance and management at work.


Robert Bacal

Bacal's Books
About The Company
About Our Performance Management Philosophy
Privacy Policy

Our Related Websites

Leadership Resource Center
Upgrade your understanding of modern leadership in a complex world. Stay current.

The Planning Resource Center

From strategic planning for businesses, small and large, right through to financial planning for millennials, stay current with the latest thoughts and actions on planning.

Bacal & Associates Store
Free and paid guides, books, and documents on business, management and more.

Small Business Resource Center

For anyone who owns, runs or would like to start their own business. Filled with advice, tips, articles.

We Believe

  • Performance management and appraisal MUST be a partnership between manager and employee where BOTH benefit.
  • Performance management can be the lever for improved employee engagement.
  • The review process is the LEAST important part of performance management
  • If managers aren't managing employee performance, why are they there?

Get in Touch

  • Phone:
    (613) 764-0241
  • Email: ceo@work911.com
  • Address:

  • Bacal & Associates
  • 722 St. Isidore Rd.
  • Casselman
  • Ontario
  • Canada, K0A 1M0