Developing An Effective Appraisal Program Reliability-This refers to the stability or consistency of a standard,or the extent to which individuals tend to maintain a certain level of performance over time. Performance standards should be written and they should be defined in quantifiable and measurable terms. Developing An Effective Appraisal Program Reliability - This refers to the stability or consistency of a standard, or the extent to which individuals tend to maintain a certain level of performance over time. Performance standards should be written and they should be defined in quantifiable and measurable terms