Performance Appraisal Method - "Graphic Rating"
Graphic rating scales are one of the most common methods of performance appraisal. Graphic rating scales require an evaluator to indicate on a scale the degree to which an employee demonstrates a particular trait, behavior, or performance result. Rating forms are composed of a number of scales, each relating to a certain job or performance-related dimension, such as job knowledge, responsibility, or quality of work. Each scale is a continuum of scale points, or anchors, which range from high to low, from good to poor, from most to least effective, and so forth. Scales typically have from five to seven points, though they can have more or less. Graphic rating scales may or may not define their scale points.
Acceptable rating scales should have the following characteristics:
1. Performance dimensions should be clearly defined.
2. Scales should be behaviorally based so that a rater is able to support all ratings with objective, observable evidence.
3. Abstract trait names such as "loyalty," "honesty," and "integrity" should be avoided unless they can be defined in terms of observable behaviors.
4. Points, or anchors, on each scaled dimension should be brief, unambiguous, and relevant to the dimension being rated. For example, in rating a person's flow of words, it is preferable to use anchors such as "fluent," "easy," "unimpeded," "hesitant," and "labored," rather than "excellent," "very good," "average," "below average," and "poor."
Carefully constructed graphic rating scales have a number of advantages:
1. Standardization of content permitting comparison of employees.
2. Ease of development use and relatively low development and usage cost.
3. Reasonably high rater and ratee acceptance.
A disadvantage of such rating scales is that they are susceptible to rating errors which result in inaccurate appraisals. Possible rating errors include halo effect, central tendency, severity, and leniency. The halo effect occurs when a rating on one dimension of an appraisal instrument substantially influences the ratings on other dimensions for the same employee. As a result of the halo effect, an employee is rated about the same across all performance dimensions. Central tendency is a lack of variation or difference among ratings of different subordinates, wherein most employees tend to be rated as average. Leniency refers to an evaluator's tendency to rate most employees very highly across performance dimensions, whereas severity refers to the tendency to rate most employees quite harshly.