How Many Response Categories are Enough for Likert Type Scales?
An Empirical Study Based on Item Response Theory
Keywords:
Likert-type scale, response categories, item response theoryAbstract
The current study investigates the optimum number of response categories for the Likert type of scales under the item response theory (IRT). The data was collected from university students that attends to mainly medicine and education faculties. A form of the “Social Gender Parity Scale” developed by Gözütok et al. (2017) was prepared, which had 3, 5 and 7-point response categories. Graded response model (GRM) was used for item calibrations. The results of the study showed that in scale development studies, using a 5-point response option provides advantages over using a 3-point response category by reliability and test information perspective. In addition, it does not pose a major disadvantage compared to a 7-point response category. Therefore, researchers are recommended to use a 5-point response category, also considering the ease of responding.
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