# Jacob Cohen (statistician)

Jacob Cohen (April 20, 1923 – January 20, 1998) was an American psychologist and statistician best known for his work on statistical power and effect size, which helped to lay foundations for current statistical meta-analysis and the methods of estimation statistics. He gave his name to such measures as Cohen's kappa, Cohen's d, and Cohen's h.

## Power analysis and significance testing

In addition to being an advocate of power analysis and effect size, Cohen was a critic of reliance on, and lack of understanding of, significance testing procedures used in statistics, especially misunderstandings of null hypothesis significance testing. In particular, he identified the "near universal misinterpretation of p as the probability that H$_0$ is false, the misinterpretation that its complement is the probability of successful replication, and the mistaken assumption that if one rejects H$_0$ one thereby affirms the theory that led to the test". He encouraged instead a recognition of single studies as exploratory and a reliance on replication for support.

## Career

A graduate of City College, he received his PhD in clinical psychology at New York University in 1950. Between 1959 and retirement in 1993 he worked in the psychology department at New York University, latterly as the head of the quantitative psychology group.
He was awarded the Distinguished Lifetime Achievement Award by the American Psychological Association in 1997 and was a fellow of the American Association for the Advancement of Science, the American Psychological Association and the American Statistical Association.

## Selected works

Below are listed some of Cohen's works. Where multiple authors are present, full names are used to facilitate reader searches for other works by those authors.
* Jacob Cohen (1960), "A coefficient of agreement for nominal scales", Educational and Psychological Measurement, 20 (1): 37–46, doi:10.1177/001316446002000104, hdl:1942/28116, S2CID 15926286
* Jacob Cohen (October 1968), "Weighted kappa: Nominal scale agreement provision for scaled disagreement or partial credit", Psychological Bulletin, 70 (4): 213–220, doi:10.1037/h0026256, PMID 19673146
* Jacob Cohen (1968), "Multiple regression as a general data-analytic system" (PDF), Psychological Bulletin, 70 (6): 426–443, CiteSeerX 10.1.1.476.6180, doi:10.1037/h0026714, archived from the original (PDF) on 11 June 2011, retrieved 11 July 2010
* Jacob Cohen (1988), Statistical Power Analysis for the Behavioral Sciences (2nd ed.), New Jersey: Lawrence Erlbaum Associates, ISBN 978-0-8058-0283-2, retrieved 24 November 2023
* Jacob Cohen (1992), "A power primer" (PDF), Psychological Bulletin, 112 (1): 155–159, doi:10.1037/0033-2909.112.1.155, PMID 19565683, archived from the original (PDF) on 20 July 2011, retrieved 10 July 2010
* Jacob Cohen (June 1992), "Statistical power analysis" (PDF), Current Directions in Psychological Science, 1 (3): 98–101, doi:10.1111/1467-8721.ep10768783, JSTOR 20182143, S2CID 144390805, archived from the original (PDF) on 3 March 2016, retrieved 10 July 2010
* Jacob Cohen (December 1994), "The Earth is round (p < .05)" (PDF), American Psychologist, 49 (12): 997–1003, doi:10.1037/0003-066x.49.12.997, archived from the original (PDF) on 20 January 2012, retrieved 11 July 2010
* Patricia Cohen; Jacob Cohen (1996), Life Values and Adolescent Mental Health, New Jersey: Lawrence Erlbaum Associates, ISBN 978-0-8058-1774-4, retrieved 10 July 2010
* Michael Borenstein; Hannah Rothstein; Jacob Cohen; David Schoenfeld; Jesse Berliln; Edward Lakatos (2001), Power and Precision: A computer program for statistical power analysis and confidence intervals, Englewood, New Jersey: Biostat, Inc, ISBN 978-0-9709662-0-9, retrieved 10 July 2010
* Jacob Cohen; Patricia Cohen; Stephen G. West; Leona S. Aiken (2003), Applied Multiple Regression/Correlation Analysis for the Behavioral Sciences (3rd ed.), New Jersey: Lawrence Erlbaum Associates, ISBN 978-0-8058-2223-6, retrieved 10 July 2010