4. Common Rating Errors and Biases

Managers must be aware of biases that distort evaluations:

1. Halo Effect

One strong positive trait affects the entire rating.

2. Horn Effect

One negative trait drags all ratings down.

3. Recency Bias

Recent events overshadow the whole year.

4. Leniency Bias

Rating everyone too highly to avoid conflict.

5. Severity Bias

Rating too harshly regardless of performance.

6. Central Tendency

Giving all “average” ratings to avoid extremes.

7. Similar-to-Me Bias

Favoring employees who share the manager’s characteristics.

8. Contrast Error

Comparing employees to each other instead of the standard.

How to Avoid Bias

• Rely on documented evidence

• Use multiple data sources

• Calibrate with other managers

• Follow the rating scale strictly

• Reflect on personal assumptions