Study of the optimal number of rating bars in the likert scale

Abstract

The Likert scale is often used in subjective knowledge management (e.g., assessment and decision making) in enterprise systems. The scales typically have 5, 7, or 9 number of rating bars. A controversial issue is: what would be an optimal number of rating bars (5, 7, or 9) for a particular application problem or for all problems? The study reported in this paper addressed this issue. The study particularly restricted to the number of rating bars being 5, 7, and 9 (denoted as S5, S7, S9), as they are commonly used in practice. A cell phone interface design was taken as a test-bed, and twenty participants were involved in the experiment. A new criterion to evaluate a subjective rating scale was developed first and then the experiment was carried out. The study concluded that S7 is the best among the three scales. The contribution of this paper includes: (1) confirming that different numbers of rating bars in a subjective rating scale can have significant effects on the subjective measurement or assessment and (2) providing a new criterion to evaluate a subjective rating scale.