What is one common mistake in evaluating personnel?

The error of central tendency refers to a tendency in performance evaluations where evaluators are prone to rate most employees near the center of a rating scale, avoiding extreme ratings. This can lead to a lack of differentiation among employee performance levels, as outstanding or underperforming employees may be rated similarly to average employees. This common mistake can result in a failure to recognize exceptional talent or to address performance issues adequately, ultimately hindering proper personnel development and motivation.

In contrast, other options describe different biases or issues that can arise in evaluations, but they do not encapsulate the widespread tendency to stick to the middle of the rating scale that the error of central tendency represents. Understanding this mistake is crucial for supervisors to improve the accuracy and effectiveness of their personnel evaluations.