Lies, damned lies, and statistics. Hacking the P-value.

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Hoping to inspire you, take a read at Damiano Cerasuolo’s article “Lies, damned lies, and statistics. Hacking the P-value“, from the last Euronet Newsletter:

In chapters from ‘my Autobiography’ Mark Twain says: “there are three kinds of lies: lies, damned lies, and statistics.” [1] Twain’s statement about the use and the misuse of statistics couldn’t have been more farsighted. On February 2016, 177-year-old American Statistical Association (ASA) released a statement [2] (followed by a scientific publication [3]) issuing guidelines of p value to conduct and interpret quantitative science. P-value is misused. P-value is usually used to test (and possibly dismiss) the “null hypothesis”. If the statistical test of two groups or pair of characteristics results in a P-value below 0.05, the null hypothesis is usually dismissed (depending on the level of significance intended): there is a relationship between the two groups (or the two characteristics) that is not attributable to mere chance. On more practical basis, we want to test the association between two factors, for example age and injectable drug use in two comparable groups issued from a specific population. If our statistical test results in a p-value of less than 0.05, the association between the two factors is usually statistically significant. However, a significant P-value doesn’t provide any information about the strength of the relationship between the two factors, neither about its direction. Criticism of the p-value is not new. On February 25th, 2015, the journal Basic and Applied Social Psychology issued an editorial [4] banning P-values and confidence intervals from all future papers. Undoubtedly these drastic steps could seem counterproductive but they have the merit to start the debate. Without proposing a ban of P-value results, the American Statistical Association observes “good statistical practice is an essential component of good scientific practice”. Meanwhile its executive director, Ron Wasserstein, explains that “wellreasoned statistical arguments contain much more than the value of a single number and whether that number exceeds an arbitrary threshold. The ASA statement is intended to steer research into a ‘post p<0.05 era’”. In other words, P-value should not substitute scientific reasoning but it should come together with numerical and graphical summaries of data, interpretation and understanding of the phenomenon under study and its results in context. Wrong P-value reporting is helping “bad” science being published: without information and with only P-value results, nonsignificant data can easily make its way through publication. Stanford metaresearcher John Ioannidis and colleagues found an increasing number of articles reporting P-values over time[5]. Almost all articles and abstracts with P-values reported statistically significant results while confidence intervals, Bayes factors, or effect sizes were rarely mentioned. The explanation to this phenomenon has already its own name: publication bias (for statistical significance). Daniël Lakens in a 2015 paper published by PeerJ [6] defines publication bias as ‘tendency to publish statistical significant results, both because authors are more likely to submit these results and reviewers and editors to evaluate more positively these manuscripts’. In the way publication bias sacrifices reproducibility (the ability to recompute results) and replicability (the chances other experimenters will achieve a consistent result) to publication itself[7], addressing this issue is urgent. Statistics are a core part of Public Health and although P-value debate could be perceived as “pure statistics”, it is not. Public Health ranges from epidemiology to hygiene, from biostatistics to health promotion. It is not a unitary, monolithic discipline and it requires a multidisciplinary approach to the “P-value gate”, in order to provide the best answers to each subdiscipline. Specialists in public health should join the debate, proposing solutions.

Damiano Cerasuolo

Euronet France


[ 1 ],_damned_lies,_and_statistics


[3] Ronald L. Wasserstein , Nicole A. Lazar. The ASA’s statement on p-values: context, process, and purpose. The American Statistician. http://d

[4] David Trafimow & Michael Marks (2015) Editorial, Basic and Applied Social Psychology, 37:1, 1-2, DOI: 10.1080/01973533.2015.1012991

[5] Chavalarias D, Wallach J, Li A, Ioannidis JA. Evolution of Reporting P Values in the Biomedical Literature, 1990-2015. JAMA. 2016;315(11):1141-1148. doi:10.1001/jama.2016.1952.

[6] Lakens D. (2015) On the challenges of drawing conclusions from p-values just below 0.05. PeerJ3:e1142

[7] Jeffrey T. Leek and Roger D. Peng Opinion: Reproducible research can still be wrong: Adopting a prevention approach. PNAS 2015 112 (6) 1645-1646; doi:10.1073/pnas.1421412111

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The EuroNews MRPH N°5 of 2014 is now available online! We invite you to discover:

  • The editorial of our President, Rocío Zurriaga Carda
  • An overview of the seminar held in Palermo (Italy) on International opportunities for Public Health training, by Guido Maringhini
  • A summary on the New Health Law project in France, by Anca Vasiliu
  • The UK Ebola response and screening at Ports of Entry, by Rebecca Nunn
  • An article about the Residency in Public Health Croatia, by Vesna Stefancic and Maja Vajagic
  • Info about the next EuroNet MRPH Meeting that will be hold in Milan (Italy) on 20-21 March 2015
  • The “all you need to know about EuroNet MRPH” section
  • And many other very interesting articles and short news from the member countries of EuroNet MRPH !!!

The newsletter could be download here EuroNews MRPH – 5_Winter_2014  in PDF format is readable with Adobe Reader or others PDF readers.

This last issue was edited by Salvo Parisi and EuroNet MRPH Italy.

We hope you will enjoy the reading and we thank you for your support!


The fourth Newsletter of Euronet MRPH is now online!

Summary :

  • An editorial from Rocio Zurriaga Carda and Guido Maringhini
  • An overview of our last meeting in London
  • Resident Experiences, resident and tutor experience in Spain
  • News around Europe
  • An article about the Ebola outbreak in Western Africa
  • And much more !!



The newsletter could be Download here (2.0 Mo, PDF). PDF format is readable with Adobe Reader or others PDF readers.

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Euronet Newsletter 3


The third Newsletter of Euronet MRPH is now online!

Summary :

  • The editorial from our president Rocio Zurriaga and former President  André Peralta
  • An overview of our last meeting in Madrid
  • Resident Experiences, the strive for the promotion of international exchanges in public health by Stefano Marventano
  • News around Europe
  • And much more!

The newsletter could be downloaded here (1.37 Mo, PDF). PDF format is readable with Adobe Reader or others PDF readers.

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Euronet Newsletter 2

The summer newsletter of Euronet MRPH is now online! We offer you to discover :

  • The editorial from our president, André Peralta
  • An overview of our last meeting in Paris
  • An article about the residency in the Netherlands, by our Dutch colleague, Karlijn Kampman
  • The “all you need to know about EuroNet MRPH” article
  • And much more!

The newsletter could be downloaded here (2.2 Mo, PDF). PDF format is readable with Adobe Reader or others PDF readers. It was created by Maël Barthoulot and the working group for the newsletter.

Enjoy the reading !

Euronet Newsletter 1 – June 2013

The first Newsletter of Euronet is now online! You will find inside :

  • An editorial from our actual president
  • An overview of the Euronet Strategy for 2013
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  • News about actual projects
  • Call for Collaborative Projects
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The newsletter could be downloaded here (2.3 Mo, PDF). PDF format is readable with Adobe Reader or others PDF readers. It was created by Maël Barthoulot and the working group for the newsletter.