Psychological Distance Between Categories in the Likert Scale: Comparing Different Numbers of Options
How to determine the number of options of Likert-type item has been investigated since more than 30 years ago. In the beginning, researchers studied the issue with respect to statistical reliability and they found that higher reliability comes from larger categories of polytomous item, and 7-point scales in particular. However, some researches indicated that reliability is independent of the number of options. In the present study, the authors evaluated the appropriate number of options by other viewpoint of equal psychological distance between categories. A new scale value formulation was developed and data collected from 772 students on 4-, 5-, and 7-point scale. Descriptive statistics, reality, Cronbach alpha, and scale values were reported. Results indicated that 1) participants tended to select somewhat negative answers and avoided selecting extreme categories in the case of 7-point scale; 2) the coefficient of reliability was independent of the number of categories in present study; and 3) the psychological distance deviated more as the number of categories increased in the BF-N and BF-ER subscales.
Questions:
1) Can the proposed method be a valid instrument to evaluate appropriate number of options should be or content of Likert-type items need to be revised when the assumptions of equal distance between categories was not holded?