  Accurate assessment of students' ability is the key task of a test.
Assessments based on final responses are the standard. As the infrastructure
advances, substantially more information is observed. One of such instances is
the process data that is collected by computer-based interactive items, which
contain a student's detailed interactive processes. In this paper, we show both
theoretically and empirically that appropriately including such information in
the assessment will substantially improve relevant assessment precision. The
precision is measured empirically by out-of-sample test reliability.
