Abstract
Research-based learning places strong emphasis on reflective thinking because of its role in developing research competence and supporting lifelong learning. However, the absence of a validated self-report scale makes it difficult for researchers and educators to assess research students' reflective thinking in a timely and cost-effective manner. To respond to this need, the present study developed the Reflective Thinking Inventory (RTI) for postgraduate research students. Using data from 454 participants, the RTI was empirically validated through cross-validation analyses. The final scale consisted of 14 items grouped into two factors: process reflection (evaluating what and how they conducted their research) and premise reflection (examining personal assumptions or contextual issues relevant to their research). The RTI demonstrated acceptable reliability, convergent and discriminant validity, and strong measurement invariance across participant subgroups. Furthermore, both of the RTI factors were positively associated with research competence. The validated RTI provides a practical tool for measuring reflective thinking among research students and for informing programme design and evaluation.