We aim to propose an index to evaluate the level of educational success performed in line with curriculum policy.We will point out that there exist two conditions for checking the improvement of the educational performance by teachers at universities. Enhancing various teaching skills by "student evaluation" and/or "classroom observation" can be regarded as a "necessary condition" but not "sufficient condition". Therefore, we propose the "sufficient condition" to obtain satisfactory educational results based on university curriculum policy. Because, the curriculum is systematically constructed by each department according to its own educational policy, this "sufficient condition" plays the role of evaluating the validity of the policy itself. We strongly suggest that the "annual transition of the GPA distribution" becomes a suitable candidate for this "sufficient condition". In addition, we would like to mention that this work of proposing the index is a good result of the Institutional Research accomplished by the ideal collaboration between academic and office staff. The latter deal with the various data of students.