What Is The Central Tendency Bias?

Central tendency bias refers to a tendency for raters, or managers to evaluate most of their employees as "average" when they apply a rating scale. So, for example, given a scale that runs with points on it that run from one (poor) to seven (excellent), with four being the average, many managers will refuse to use the points at either of the ends. There will be a tendency for almost all ratings to fall

within the 3-5 range. This can be problematic since a very poor employee may be rated slightly above average even though this rating is inaccurate, or, on the other side, a superior employee may be rated in that same 3-5 range even though he or she deserves a more excellent rating.

Shorter rating scales (e.g. those with only three points, rather than seven) tend to cause less central tendency bias, but they also become less exact.

You've probably heard managers say, "I never rate people as excellent." This is an example of central tendency bias.