Psychological Distance Between Categories in the Likert Scale: Comparing Difference
Numbers of Options
Takafumi Wakita, Natsumi Ueshima, and Hiroyuki Noguchi
Typically, it was assumed that the psychological distance between the categories
is equal in the Likert scale. In the present study, the assumption is relaxed to the
assumption that the scale value of the pth category is normally distributed and could
be estimated directly.
It was found that the numbers of options did affect the psychological distance
between categories (especially for the 7-point scales) but not affect the descripted
statistics and reliability.
Questions:
1. Is it realistic to assume the scale value of the pth category is normally
distributed?
2. What is the assumption of the psychological distance between the categories for
Partial Credit Model? Is it still equal psychological distance?
3. The Random Effect Rating Scale Model (RERSM) in Wang, Wilson and Shih (2006)
also concerned the variation of the thresholds across the persons. The difference
between the RERSM and the model in the present study lies in that the RERSM
focused on the variation within the categories, not between the categories. The
REPCM which combined with the RERSM and Partial Credit Model is a more
generalized model than the model developed in the present study.