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Correlation coefficients in medical research: from product moment correlation to the odds ratio

Helena Chmura Kraemer1

  • 1Department of Psychiatry and Behavioral Sciences, Stanford University, 401 Quarry Road, MC5717 Stanford, CA 94305, USA. hck@stanford.edu

Abstract

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Odds Ratio

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Hazard Ratio

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Correlations

Correlation means that there is a relationship between two or more variables (such as ice cream consumption and crime), but this relationship does not necessarily imply cause and effect. When two variables are correlated, it simply means that as one variable changes, so does the other. We can measure correlation by calculating a statistic known as a correlation coefficient. A correlation coefficient is a number from -1 to +1 that indicates the strength and direction of the relationship between...
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Coefficient of Correlation

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Survival analysis is a cornerstone of medical research, used to evaluate the time until an event of interest occurs, such as death, disease recurrence, or recovery. Unlike standard statistical methods, survival analysis is particularly adept at handling censored data—instances where the event has not occurred for some participants by the end of the study or remains unobserved. To address these unique challenges, specialized techniques like the Kaplan-Meier estimator, log-rank test, and Cox...