P values and the art of herding cats

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"Repligate: reproducibility in statistical studies. What does it mean and in what sense does it matter?"

P Values and the art of herding catsStephen Senn(c) Stephen Senn1

Talk given at RSS Manchester

I consider the problems that the ASA faced in getting a P-value statement together, not in terms of the process, but by looking at the expressed opinion of 21 published commentaries of the agreed statement. I then trace history of the development of P-values. I show that the perceived problem with P-values in not just one of a supposed inadequacy of frequentist statistics but reflects a struggle at the very heart of Bayesian inference. I conclude that replacing P-values by automatic Bayesian approaches is unlikely to abolish controversy. It may be better to try and embrace diversity than to pretend it is not there.

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Acknowledgements(c) Stephen Senn2Acknowledgements

Thanks to the ASA and the RSS for inviting me

This work is partly supported by the European Unions 7th Framework Programme for research, technological development and demonstration under grant agreement no. 602552. IDEAL

OutlineAspects of the ASA statementA brief history of P-valuesThe real (hidden) reason why P-values are so controversialConclusions(c) Stephen Senn3

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So you though the ASA statement was wishy washy?(c) Stephen Senn4You can believe me that had it been any stronger, then all but one of the statisticians would have resigned.

Who would not have resigned would have been the one whose proposal would have been adopted.

If only the rest could have agreed with me, we would have had a much stronger statement.

(c) Stephen Senn5The collective noun for statisticians is a quarrel

John Tukey

An Example of the ProblemIf you want to avoid making a fool of yourself very often, do not regard anything greater than p