title: Statistical significance versus clinical relevance.
abstract: In March this year, the American Statistical Association (ASA) posted a statement on the correct use of P-values, in response to a growing concern that the P-value is commonly misused and misinterpreted. We aim to translate these warnings given by the ASA into a language more easily understood by clinicians and researchers without a deep background in statistics. Moreover, we intend to illustrate the limitations of P-values, even when used and interpreted correctly, and bring more attention to the clinical relevance of study findings using two recently reported studies as examples. We argue that P-values are often misinterpreted. A common mistake is saying that P < 0.05 means that the null hypothesis is false, and P ≥0.05 means that the null hypothesis is true. The correct interpretation of a P-value of 0.05 is that if the null hypothesis were indeed true, a similar or more extreme result would occur 5% of the times upon repeating the study in a similar sample. In other words, the P-value informs about the likelihood of the data given the null hypothesis and not the other way around. A possible alternative related to the P-value is the confidence interval (CI). It provides more information on the magnitude of an effect and the imprecision with which that effect was estimated. However, there is no magic bullet to replace P-values and stop erroneous interpretation of scientific results. Scientists and readers alike should make themselves familiar with the correct, nuanced interpretation of statistical tests, P-values and CIs.
authors.affiliation: Department of Nephrology, Radboud Institute of Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.|Centre for Research in Epidemiology and Population Health, CESP, Université Paris-Saclay, Université Paris-Sud, UVSQ, Inserm, Villejuif, France.
authors.forename: Marieke H C
authors.initials: MHC
authors.lastname: van Rijn
authors.affiliation: Department of Nephrology, Radboud Institute of Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Anneke
authors.initials: A
authors.lastname: Bech
authors.affiliation: Centre for Research in Epidemiology and Population Health, CESP, Université Paris-Saclay, Université Paris-Sud, UVSQ, Inserm, Villejuif, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Bouyer
authors.affiliation: Department of Nephrology, Radboud Institute of Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Jan A J G
authors.initials: JAJG
authors.lastname: van den Brand
mesh_terms: D016001:Confidence Intervals; D003627:Data Interpretation, Statistical; D006801:Humans; D013223:Statistics as Topic
keywords: P-value; P-value function; confidence interval; epidemiology; statistical analysis