The purpose of this study is to investigate whether the expression of items used to examine personal epistemological beliefs could affect the probabilities of response for compared groups and research outcomes. Differential-item-functioning (DIF) analysis on school types and location of school according to the Rasch model was performed in this study. Nonacademically inclined school students (n = 212) and academically inclined school students (n = 197) were selected to complete the questionnaire. The questionnaire consisted of three dimensions of beliefs about knowing and two dimensions of beliefs about learning. The results of the DIF analysis suggested that the items in the dimensions about knowing favor academically inclined students and students from schools located in the northern areas of Taiwan. The items in the learning dimensions favor nonacademically inclined students and students from schools located in the southern areas of Taiwan. The group comparisons were different between the scale that included the DIF items and the scale that excluded the DIF items. The discussion addresses the value of the precise detections for inappropriate items and the effect of the academic achievement on completing the survey.