A disaster manager must be able to evaluate staff members in order to make effective staffing decisions during the transitions between phases of a disaster and to help improve the performance of the operation by determining what aspects of an individual's work needs improvement. Criteria for personnel appraisal and measures of performance, objective or subjective, are essential to conduct a fair and thorough evaluation. Errors introduce bias into the appraisal in the form of a “halo” effect, harsh or lenient ratings, a central tendency error, or recency effect, but recognition of these errors helps reduce their effect. A results-based appraisal program is favored because it focuses on what the worker achieves. Regular appraisal periods are suggested for optimal improvement in performance. Suggestions are given for an effective personnel appraisal, such as focusing on positive work performance, being aware of biases in judging people, and being specific when citing examples of work performance.