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Friday, 20.10.2017

Comment (Martin M. Katz)

There are several somewhat unusual aspects to Per Bech’s book on Clinical Psychometrics. First, despite the great need for a historical treatment of how the relatively new science, neuropsychopharmacology, developed quantified methods for psychopathology and the capacity to measure treatment-induced change, no one has come forth to do this important job. Bech not only provides the historical perspective but he manages by surveying recent research to sort out the various rating and other psychological methods that have been developed over several decades, highlighting the continuing controversies that exist in regard to measurement strategy and technical details that underlie method development. We expect a psychologist to write this type of book. It is unusual of course that Bech as a psychiatrist, has fortunately, most of the skills to carry off this very complicated task.

This is not a book, however, that psychiatrists will rush to buy. They are not generally comfortable with quantifying their clinical judgments and have rather little exposure to any training in this area. Contrary to the general belief that psychologists have paved the way for the construction and acceptance of rating methods in clinical research, Bech presents another view. He identifies Kraepelin and Hamilton, two of the most prominent psychiatrists on the world scene as the leaders here. By making a case for that conclusion, he might inadvertently enlist a great many psychiatrists in the further development of this field. Bech actually balanced this view in the text, by also describing the prominence of Galton, Spearman, Eysenck, the contributions of Maurice Lorr and John Overall, and several other psychologists. To fully appreciate what is covered, e.g., which scales are currently available and what they are capable of measuring, we note the clarity with which he presents this information and his particular perspective on the right kind of strategy and associated technologies for constructing these instruments.

Bech classifies test development into two periods, the “classical” and “modern”. In describing factor analysis he contrasts supporters of the two factors versus those who rely on rotations and thereby, uncover a multi-factorial structure of psychopathology. Beyond that he cites limitations of factor analysis, generally, pointing out that it cannot be used to validate phenomena, but more importantly, is not designed to develop methods, but only to provide classification of variables. He appears to be convinced that the age of factor analysis is over, and that the field should move on the use of the "item response" model. He sees the latter method as better suited to solving the problems in this field. I am not sure here, however, that his glossary definitions of “validity” which stress clinical significance and unidimensionality, correspond to the commonly accepted psychometric definition; I,e , the simpler notion that validity is the extent to which a method measures what it purports to measure,  I, therefore, think I understand his stance on the number of factors, but take issue with his conclusion. He like Max Hamilton and Pierre Pichot appear committed to brief scales and the two factor approach. Those on the other side of the issue conceive of each of the disorders as multifaceted and utilize factor analysis to uncover their dimensional structures.

Thus, the factor analysts view it as a data reduction method aimed at uncovering the two or more components that can most parsimoniously explain what the method is actually measuring. Further, when the disorder is conceived to be multidimensional it is then necessary to identify each of the components, and from the factor analysis results, create ways of quantifying them.  Currently that is done through principle components analysis and rotation. Bech presents thoughtful views on these matters but does not do justice to the multifactor approach. A historical example of the contrasting lines of thinking here are where he focuses on the Hamilton Depression Scale (Ham-D) and the Brief Psychiatric Rating Scale (BPRS), brief scaies, but provides limited information on their predecessors, the Wittenborn Psychiatric Scales and Lorr’s Inpatient Multidimensional Psychiatric Scales, both multifactorial scales. In these two cases the authors’ targets were the facets of psychopathology and the importance of developing a set of items for each of these facets. The basic psychometric principle followed was that more reliable and valid measures of the components, e.g., “anxiety”, can be achieved by having the judges rate a set of observed behaviors that reflect that component, than by having an observer rate a more complex, global concept  such as “anxiety”. It was Lorr, as Bech points out, who wrote and compiled the 63 items and determined the factor structure of psychopathology. Overall and Gorham used Lorr’s factors to craft global definitions based on interpretation of his factor items, in order to create their 16 ”global” items for the original BPRS. We are aware of how well the BPRS used in hundreds of studies, worked these many years, particularly in the evaluation of change in overall severity of the disorder in drug trials.. But when it comes to reliably and validly measuring the dimensions of psychopathology, equally important in the science, the IMPS is a more effective instrument and applicable to a wider range of problems in clinical research.

This was perhaps the only shortcoming I could find in this otherwise balanced and clear-headed judgment of the major issues in our field. For psychiatry, Bech highlights in reviewing the history of the rating scales, that Kraepelin constructed his own rating method, to be followed by scales developed and modified by Max Hamilton and Pierre Pichot, all three attempting to create a functioning science for psychiatry. Their focus on the importance of scales will no doubt surprise psychiatrists and may prove a positive influence on their approach to them in clinical practice. The history Bech presents is inspiring. Not only does he elevate rating scales in the minds of researchers and clinicians but he also, following philosophers Jaspers and Wittgenstein, in restoring respect for the phenomenologic approach to characterizing the nature of psychopathology.

I heartily recommend this book as a text for Clinical Methods courses for psychologists and psychiatrists. I view Per Bech’s effort as filling a significant gap in the practice of current clinical research and an important contribution to the science of psychopathology.

Martin M. Katz
August 1, 2013