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Wednesday, 22.03.2017

Reply (Per Bech)

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In the scientific game the dialogue between the author of a submitted manuscript and the journal’s referees is quite essential.

Traditionally, however, the dialogue between the author of a book and an invited reviewer of this book is considered outside the scope of this game and quite inappropriate. The progressive aspect of the INHN is to break down this tradition so as to increase the interest in scientific games in the name of research.

Martin Katz’ review of my Clinical Psychometrics has exactly captured my reason for publishing this book, namely by its reference to Kraepelin, Hamilton and Pichot to awaken the minds of clinical psychiatrists to the uses of rating scales. Generally psychiatrists are, as pointed out by Martin Katz, uncomfortable with the quantifying of their clinical judgements and they often have rather little exposure to any training with these scales. A shortcoming of my book, as stated by Martin Katz, is the treatment of factor analysis. With reference to Ockham's razor, i.e. the principle of simplicity (the law of parsimony), I have preferred to focus on the first two components when interpreting the results from a principal component analysis. My book is essentially concerned with the psychometric validation procedure which demonstrates whether items in a rating scale can objectively measure dimensions of clinical severity (e.g. degrees of schizophrenicity, degrees of depressiveness, or degrees of neuroticism). In this connection item response models are the psychometric validation of measurement to be used when demonstrating these dimensions of severity i.e. that the total score of a rating scale is a sufficient statistic.

The importance of factor analysis or principal component analysis does not lie with the measurement issue but, as stated by Martin Katz, in identifying the multi-facets of, for example, depression. In patients with treatment-resistant depression I have actually used principal component analysis and identified a principal component which encompass concentration problems, fatigability, lassitude, and sleep problems. Furthermore, I employed item response theory models to measure the severity of this neuropsychiatric or neuropsychological syndrome. The importance of factor analysis is its ability to explore for new dimensions but the clinical relevance is outside the explorative nature of factor analysis.

Martin Katz has for many years as a psychologist worked very close together with psychiatrists in the field of psychopharmacology, especially in depression. I appreciate his very balanced review of my book. It has really been my goal to: “fill a significant gap in the practice of current clinical research”.

Per Bech
August 29, 2013