Psychological Distance Between Categories in the
Likert Scale: Comparing Different Numbers of Options
TakafumiWakita1, Natsumi Ueshima, and Hiroyuki Noguchi
Educational and Psychological Measurement
The purpose of the article is to examine the appropriate number of categories for Likert scales, focusing on the psychological distance between categories, and clarify how the number of options affects this distance. The authors proposed a new algorithm for calculating the scale values of options by applying item response theory and the ideas of Wakita to reveal the influence of the number of categories.
11 neuroticism items (BF-N) and 12 extraversion items (BF-extraversion normal [EN] and BF-extraversion reversed [ER]) of the Big Five Scale (Wada, 1996) were selected for the illustration.
The 4-, 5-, and 7-point scales were used for the same personality scale. The 4-point scale was adopted based on its frequency of use and participants’ satisfaction of expressing their feelings (Preston & Colman, 2000); the five-pont scale was set up based on its frequency of use and ease of selecting an answer (Preston & Colman, 2000), and a 7-point scale was set up based on the higher reliability of this number of options shown by Cicchetti, Showalter, and Tyrer. (1985), Oaster (1989), and Preston and Colman (2000).
In this study, the results show that the number of categories did not influence the descriptive statistics and the estimates of the reliability coefficient, but it did influence the item values.
The results also suggest that it was not necessary to adapt the 7-point scale, which requires more time, and that the psychological distance was sensitive to items with socially negative contents.
The paper is very easy to understand. The logical is very clear.
If the study uses the simulation to manipulate the number of categories, the results will be more convincing. For the empirical study, there is no way to judge the absolute difference. We can just get the results by comparison. We do not know to what extent the result will be the differences.