Using mixed methods to develop new scales is not a new idea since the 2000s. However, there exists inadequate literature that discusses scale development using mixed methods, with steps including how to design the study, how to implement the process, and how to conduct validation. This study proposes a hands-on model of using mixed methods to…

This paper presents the authors' critique on "Clarifying the Consensus Definition of Validity" by Paul E. Newton (this issue). There are serious differences of opinion regarding the topic of validity. Newton is aware of these differences, as made clear by his choice of references and particularly his effort to respond to the various Borsboom…

Teacher knowledge has been of theoretical and empirical interest for over two decades, and development of measures is overdue. The researchers represented in this volume have been breaking new ground by developing a measure of mathematical knowledge for teaching (MKT) without guiding precedents, and in the face of differing perspectives on teacher…

Operating from multiple literature bases in cognitive psychology, mathematics education, and theoretical and applied psychometrics, Schilling, Hill and their colleagues provide a systemic approach to studying the validity of scores of mathematical knowledge for teaching. This system encompasses an array of task formats and methodologies. The…