In this research, the problem-solving abilities of students in a Problem-Based Learning (PBL) course, held over a year, were observed through two performance assessments, at the end of the first and second semesters, respectively. Learning processes, such as studentsʼ approach and attitude toward learning in the course, were also evaluated through surveys individually completed by the students. These learning processes (indirect assessments) were then analyzed for their power to explain changes in the studentsʼ problem-solving abilities (direct assessments), and an integration of the direct and indirect assessments was attempted. First, through an analysis of the reliability of learning-process measurements from the perspectives of consiste...