Jacob Cohen, PhD, 1923-1998 | JAMA Psychiatry | JAMA Network
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June 1999

Jacob Cohen, PhD, 1923-1998

Arch Gen Psychiatry. 1999;56(6):581. doi:10-1001/pubs.Arch Gen Psychiatry-ISSN-0003-990x-56-6-yot8401

Jacob Cohen , a pioneer in the field of research methods, died on January 20, 1998, at the age of 74 years. All who work in the field of psychiatric research were touched in many important ways by Jack's contributions. Those who had the opportunity to work with him were enriched also by his warmth, his sense of humor, and his friendship.

Jacob Cohen, PhD

Jacob Cohen, PhD

Jack grew up in New York. He graduated early from high school and enrolled in City College of New York at the age of 15 years. He left college and served in Army Intelligence in Europe during World War II. On his return he completed work on his bachelor's degree and then earned a PhD in clinical psychology at New York University, where he also spent most of his teaching career.

Jack had unique abilities as an author and teacher. His clarity of thought and his ability to make difficult concepts seem intuitive were unique, but Jack went far beyond this. His writings are marked by a keen sense of perspective that enabled him to focus on issues of practical importance. They are marked also by his sense of humor. Jack would write about statistics in a way that led the reader to smile and sometimes even to laugh out loud.

A listing of Jack's contributions to our field during the past 3 decades reads like a road map of key issues that researchers have addressed in this period. Early in his career Jack recognized the need for a measure of interrater agreement for nominal scales and created Cohen's kappa, which quickly became and remains the key index used for this purpose. While Jack insisted that he had discovered, rather than invented, power analysis, the fact is that he created the methodology that made power analysis possible and then made it available to the research community through a series of papers, texts, and computer programs. By doing so he had a profound effect on the way research is conducted, not only in psychiatry but in virtually all fields of medical and behavioral research. Working with his wife and colleague, Pat, Jack developed an expansive data analytic system around multiple regression, showing how this mechanism could be applied to the kinds of issues commonly encountered in psychiatric research. During the last few years Jack was at the vanguard of the movement to focus on effect size estimation—that is, measures of the clinical impact of interventions, rather than significance tests.

Jack was active in several professional organizations, including the Society for Multivariate Experimental Psychology, where he served as president, and the American Psychological Association, where he co-chaired the Task Force on Statistical Inference. In August 1997 the American Psychological Association honored Jack with its award for distinguished lifetime contributions.

To a generation of psychology students at New York University, Jack will be remembered as a teacher. To untold numbers of researchers Jack will be remembered for his clarity and perspective. To those with whom he worked in the causes of desegregation and acquired immunodeficiency syndrome research he will be remembered as a passionate and effective advocate. To those he might have met even briefly he will be remembered for his sense of humor and perhaps for his ability to speak at length on the distinction between shlemiel and shlemazel. Mostly, though, Jack will be remembered as a friend.

Larry Erlbaum, Jack's publisher and friend, said of him:

When Jack saw a friend, it would be as if someone had pulled a chain that lit up a bulb inside of the man, such was his generosity with friends. He could share and give of himself and do so in the most straightforward and unaffected manner. Obviously I am not impartial in the matter, but to me he was a most courageous man who fought valiantly throughout his life and all who knew him could not help but share the immense warmth and love he engendered. He is happily well past any pain and suffering. We who remain are fortunate indeed to have had the great pleasure and privilege of knowing him. There is no way I can convey the greatness and the complexity of this man, but he always will remain an example of the highest rank one could command in his eyes—a real mensch.

Jack is survived by his wife, Pat; his children, Marcia, Aviva, Erika, and Gideon; and 3 grandchildren.