private sector organizations than in public sector organizations.
Performance evaluations build a history of an individual's organizational life, and this history follows the individual throughout the length of a career. It is important, therefore, for the individual as well as the organizations that the per formance appraisal process be accurate and reliable.
Gortner (1987) stated that an effective performance evalu ation instrument or process must be objective, valid, and reli able. Objectivity in performance evaluation means that the instrument or process must provide an evaluator with a means of measuring performance criteria which does not require a subjec tive act on the part of the evaluator. Validity in a perfor mance evaluation instrument or process means that the instru ment (or procedure) really measures that which it is intended 3to measure. True validity is difficult to obtain in any evalu ation instrument or process designed to evaluate human activi ties; however, the task is made infinitely less difficult, if the definition of that which is to be measured is simplified. As an example, if a school system administration is satisfied to simply equate teacher performance with the ability of the teacher to prepare an acceptable lesson plan, then, a valid measurement may be esaily developed. If, however, the adminis tration is also interested in other aspects of teacher perfor mance, such as student teacher interaction, student perfor mance, and so forth, then, the development of a valid measure ment instrument or process increases in difficulty, as the definition of teacher performance is expanded. A reliable evaluation instrument or process is one which will yield comparable results time after time, when used for its intended purpose.
Thus, a performance evaluation instrument or process should be objective, valid, and reliable. It is difficult to argue against the inclusion of such criteria in the definitio...