Excursion 2: Taboos of Induction and Falsification: Tour I (first stop)

StatSci/PhilSci Museum

Where you are in the Journey* 

Cox: [I]n some fields foundations do not seem very important, but we both think that foundations of statistical inference are important; why do you think that is?

Mayo: I think because they ask about fundamental questions of evidence, inference, and probability … we invariably cross into philosophical questions about empirical knowledge and inductive inference. (Cox and Mayo 2011, p. 103)

Contemporary philosophy of science presents us with some taboos: Thou shalt not try to find solutions to problems of induction, falsification, and demarcating science from pseudoscience. It’s impossible to understand rival statistical accounts, let alone get beyond the statistics wars, without first exploring how these came to be “lost causes.” I am not talking of ancient history here: these problems were alive and well when I set out to do philosophy in the 1980s. I think we gave up on them too easily, and by the end of Excursion 2 you’ll see why. Excursion 2 takes us into the land of “Statistical Science and Philosophy of Science” (StatSci/PhilSci). Our Museum Guide gives a terse thumbnail sketch of Tour I. Here’s a useful excerpt:

Once the Problem of Induction was deemed to admit of no satisfactory, non-circular solutions (~1970s), philosophers of science turned to building formal logics of induction using the deductive calculus of probabilities, often called Confirmation Logics or Theories. A leader of this Confirmation Theory movement was Rudolf Carnap. A distinct program, led by Karl Popper, denies there is a logic of induction, and focuses on Testing and Falsification of theories by data. At best a theory may be accepted or corroborated if it fails to be falsified by a severe test. The two programs have analogues to distinct methodologies in statistics: Confirmation theory is to Bayesianism as Testing and Falsification are to Fisher and Neyman–Pearson.


Continue reading

Categories: induction, Statistical Inference as Severe Testing | 2 Comments

All She Wrote (so far): Error Statistics Philosophy: 7 years on

Error Statistics Philosophy: Blog Contents (7 years) [i]
By: D. G. Mayo

Dear Reader: I began this blog 7 years ago (Sept. 3, 2011)! A big celebration is taking place at the Elbar Room this evening, both for the blog and the appearance of my new book: Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars (CUP). While a special rush edition made an appearance on Sept 3, in time for the RSS meeting in Cardiff, it was decided to hold off on the festivities until copies of the book were officially available (yesterday)! If you’re in the neighborhood, stop by for some Elba Grease


Many of the discussions in the book were importantly influenced (corrected and improved) by reader’s comments on the blog over the years. I thank readers for their input. Please peruse the offerings below, taking advantage of the discussions by guest posters and readers! I posted the first 3 sections of Tour I (in Excursion i) here, here, and here.
This blog will return to life, although I’m not yet sure of exactly what form it will take. Ideas are welcome. The tone of a book differs from a blog, so we’ll have to see what voice emerges here.


D. Mayo Continue reading

Categories: 3-year memory lane, 4 years ago!, blog contents, Metablog | 2 Comments

Excursion 1 Tour I (3rd stop): The Current State of Play in Statistical Foundations: A View From a Hot-Air Balloon (1.3)


How can a discipline, central to science and to critical thinking, have two methodologies, two logics, two approaches that frequently give substantively different answers to the same problems? … Is complacency in the face of contradiction acceptable for a central discipline of science? (Donald Fraser 2011, p. 329)

We [statisticians] are not blameless … we have not made a concerted professional effort to provide the scientific world with a unified testing methodology. (J. Berger 2003, p. 4)

From the aerial perspective of a hot-air balloon, we may see contemporary statistics as a place of happy multiplicity: the wealth of computational ability allows for the application of countless methods, with little handwringing about foundations. Doesn’t this show we may have reached “the end of statistical foundations”? One might have thought so. Yet, descending close to a marshy wetland, and especially scratching a bit below the surface, reveals unease on all sides. The false dilemma between probabilism and long-run performance lets us get a handle on it. In fact, the Bayesian versus frequentist dispute arises as a dispute between probabilism and performance. This gets to my second reason for why the time is right to jump back into these debates: the “statistics wars” present new twists and turns. Rival tribes are more likely to live closer and in mixed neighborhoods since around the turn of the century. Yet, to the beginning student, it can appear as a jungle.

Statistics Debates: Bayesian versus Frequentist

These days there is less distance between Bayesians and frequentists, especially with the rise of objective [default] Bayesianism, and we may even be heading toward a coalition government. (Efron 2013, p. 145)

Continue reading

Categories: Statistical Inference as Severe Testing | 1 Comment

Excursion 1 Tour I (2nd stop): Probabilism, Performance, and Probativeness (1.2)


I shall be concerned with the foundations of the subject. But in case it should be thought that this means I am not here strongly concerned with practical applications, let me say right away that confusion about the foundations of the subject is responsible, in my opinion, for much of the misuse of the statistics that one meets in fields of application such as medicine, psychology, sociology, economics, and so forth. (George Barnard 1985, p. 2)

While statistical science (as with other sciences) generally goes about its business without attending to its own foundations, implicit in every statistical methodology are core ideas that direct its principles, methods, and interpretations. I will call this its statistical philosophy. To tell what’s true about statistical inference, understanding the associated philosophy (or philosophies) is essential. Discussions of statistical foundations tend to focus on how to interpret probability, and much less on the overarching question of how probability ought to be used in inference. Assumptions about the latter lurk implicitly behind debates, but rarely get the limelight. If we put the spotlight on them, we see that there are two main philosophies about the roles of probability in statistical inference: We may dub them performance (in the long run) and probabilism. Continue reading

Categories: Statistical Inference as Severe Testing | 3 Comments

Excursion 1 Tour I: Beyond Probabilism and Performance: Severity Requirement (1.1)

The cruise begins…

I’m talking about a specific, extra type of integrity that is [beyond] not lying, but bending over backwards to show how you’re maybe wrong, that you ought to have when acting as a scientist. (Feynman 1974/1985, p. 387)

It is easy to lie with statistics. Or so the cliché goes. It is also very difficult to uncover these lies without statistical methods – at least of the right kind. Self- correcting statistical methods are needed, and, with minimal technical fanfare, that’s what I aim to illuminate. Since Darrell Huff wrote How to Lie with Statistics in 1954, ways of lying with statistics are so well worn as to have emerged in reverberating slogans:

  • Association is not causation.
  • Statistical significance is not substantive significamce
  • No evidence of risk is not evidence of no risk.
  • If you torture the data enough, they will confess.

Exposés of fallacies and foibles ranging from professional manuals and task forces to more popularized debunking treatises are legion. New evidence has piled up showing lack of replication and all manner of selection and publication biases. Even expanded “evidence-based” practices, whose very rationale is to emulate experimental controls, are not immune from allegations of illicit cherry picking, significance seeking, P-hacking, and assorted modes of extra- ordinary rendition of data. Attempts to restore credibility have gone far beyond the cottage industries of just a few years ago, to entirely new research programs: statistical fraud-busting, statistical forensics, technical activism, and widespread reproducibility studies. There are proposed methodological reforms – many are generally welcome (preregistration of experiments, transparency about data collection, discouraging mechanical uses of statistics), some are quite radical. If we are to appraise these evidence policy reforms, a much better grasp of some central statistical problems is needed.

Continue reading

Categories: Statistical Inference as Severe Testing, Statistics | 8 Comments

The Physical Reality of My New Book! Here at the RSS Meeting


Categories: SIST | 3 Comments

RSS 2018 – Significance Tests: Rethinking the Controversy


Day 2, Wednesday 05/09/2018

11:20 – 13:20

Keynote 4 – Significance Tests: Rethinking the Controversy Assembly Room

Sir David Cox, Nuffield College, Oxford
Deborah Mayo, Virginia Tech
Richard Morey, Cardiff University
Aris Spanos, Virginia Tech

Intermingled in today’s statistical controversies are some long-standing, but unresolved, disagreements on the nature and principles of statistical methods and the roles for probability in statistical inference and modelling. In reaction to the so-called “replication crisis” in the sciences, some reformers suggest significance tests as a major culprit. To understand the ramifications of the proposed reforms, there is a pressing need for a deeper understanding of the source of the problems in the sciences and a balanced critique of the alternative methods being proposed to supplant significance tests. In this session speakers offer perspectives on significance tests from statistical science, econometrics, experimental psychology and philosophy of science. There will be also be panel discussion.

Categories: Error Statistics | 2 Comments


3 years ago...

3 years ago…

MONTHLY MEMORY LANE: 3 years ago: August 2015. I mark in red 3-4 posts that seem most apt for general background on key issues in this blog, excluding those reblogged recently[1], and in green up to 3 others of relevance to philosophy of statistics [2]. Posts that are part of a “unit” or a group count as one.

August 2015

  • 08/05 Neyman: Distinguishing tests of statistical hypotheses and tests of significance might have been a lapse of someone’s pen
  • 08/08  Statistical Theater of the Absurd: “Stat on a Hot Tin Roof”
  • 08/11 A. Spanos: Egon Pearson’s Neglected Contributions to Statistics (recently reblogged)
  • 08/14 Performance or Probativeness? E.S. Pearson’s Statistical Philosophy
  • 08/15  Severity in a Likelihood Text by Charles Rohde
  • 08/19 Statistics, the Spooky Science
  • 08/20 How to avoid making mountains out of molehills, using power/severity
  • 08/24 3 YEARS AGO (AUGUST 2012): MEMORY LANE
  • 08/31 The Paradox of Replication, and the vindication of the P-value (but she can go deeper) 9/2/15 update (ii)

[1] Monthly memory lanes began at the blog’s 3-year anniversary in Sept, 2014.

[2] New Rule, July 30, 2016, March 30,2017 -a very convenient way to allow data-dependent choices (note why it’s legit in selecting blog posts, on severity grounds).












Categories: 3-year memory lane | Leave a comment

A. Spanos: Egon Pearson’s Neglected Contributions to Statistics

Continuing with the discussion of E.S. Pearson in honor of his birthday:

Egon Pearson’s Neglected Contributions to Statistics

by Aris Spanos

    Egon Pearson (11 August 1895 – 12 June 1980), is widely known today for his contribution in recasting of Fisher’s significance testing into the Neyman-Pearson (1933) theory of hypothesis testing. Occasionally, he is also credited with contributions in promoting statistical methods in industry and in the history of modern statistics; see Bartlett (1981). What is rarely mentioned is Egon’s early pioneering work on:

(i) specification: the need to state explicitly the inductive premises of one’s inferences,

(ii) robustness: evaluating the ‘sensitivity’ of inferential procedures to departures from the Normality assumption, as well as

(iii) Mis-Specification (M-S) testing: probing for potential departures from the Normality  assumption.

Arguably, modern frequentist inference began with the development of various finite sample inference procedures, initially by William Gosset (1908) [of the Student’s t fame] and then Fisher (1915, 1921, 1922a-b). These inference procedures revolved around a particular statistical model, known today as the simple Normal model: Continue reading

Categories: E.S. Pearson, Egon Pearson, Statistics | 1 Comment

Egon Pearson’s Heresy

E.S. Pearson: 11 Aug 1895-12 June 1980.

Today is Egon Pearson’s birthday. In honor of his birthday, I am posting “Statistical Concepts in Their Relation to Reality” (Pearson 1955). I’ve posted it several times over the years, but always find a new gem or two, despite its being so short. E. Pearson rejected some of the familiar tenets that have come to be associated with Neyman and Pearson (N-P) statistical tests, notably the idea that the essential justification for tests resides in a long-run control of rates of erroneous interpretations–what he termed the “behavioral” rationale of tests. In an unpublished letter E. Pearson wrote to Birnbaum (1974), he talks about N-P theory admitting of two interpretations: behavioral and evidential:

“I think you will pick up here and there in my own papers signs of evidentiality, and you can say now that we or I should have stated clearly the difference between the behavioral and evidential interpretations. Certainly we have suffered since in the way the people have concentrated (to an absurd extent often) on behavioral interpretations”.

Continue reading

Categories: phil/history of stat, Philosophy of Statistics, Statistics | Tags: , , | 2 Comments

For Popper’s Birthday: Reading from Conjectures and Refutations (+ self-test)


28 July 1902 – 17 September 1994

Today is Karl Popper’s birthday. I’m linking to a reading from his Conjectures and Refutations[i] along with: Popper Self-Test Questions. It includes multiple choice questions, quotes to ponder, an essay, and thumbnail definitions at the end[ii].

Blog Readers who wish to send me their answers will have their papers graded [use the comments or error@vt.edu.] An A- or better earns a signed copy of my forthcoming book: Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars. [iii]

[i] Popper reading from Conjectures and Refutations
[ii] I might note the “No-Pain philosophy” (3 part) Popper posts on this blog: parts 12, and 3.

[iii] I posted this once before, but now I have a better prize.



Popper, K. (1962). Conjectures and Refutations: The Growth of Scientific Knowledge. New York: Basic Books.



Categories: Popper | 1 Comment


3 years ago...

3 years ago…

MONTHLY MEMORY LANE: 3 years ago: July 2015. I mark in red 3-4 posts from each month that seem most apt for general background on key issues in this blog, excluding those reblogged recently[1], and in green up to 3 others of general relevance to philosophy of statistics [2].  Posts that are part of a “unit” or a group count as one.

July 2015

  • 07/03 Larry Laudan: “When the ‘Not-Guilty’ Falsely Pass for Innocent”, the Frequency of False Acquittals (guest post)
  • 07/09  Winner of the June Palindrome contest: Lori Wike
  • 07/11 Higgs discovery three years on (Higgs analysis and statistical flukes)-reblogged recently
  • 07/14  Spot the power howler: α = ß?
  • 07/17  “Statistical Significance” According to the U.S. Dept. of Health and Human Services (ii)
  • 07/22 3 YEARS AGO (JULY 2012): MEMORY LANE
  • 07/24 Stephen Senn: Randomization, ratios and rationality: rescuing the randomized clinical trial from its critics
  • 07/29  Telling What’s True About Power, if practicing within the error-statistical tribe


[1] Monthly memory lanes began at the blog’s 3-year anniversary in Sept, 2014.

[2] New Rule, July 30, 2016, March 30,2017 -a very convenient way to allow data-dependent choices (note why it’s legit in selecting blog posts, on severity grounds).












Categories: 3-year memory lane | Leave a comment

S. Senn: Personal perils: are numbers needed to treat misleading us as to the scope for personalised medicine? (Guest Post)

Personal perils: are numbers needed to treat misleading us as to the scope for personalised medicine?

A common misinterpretation of Numbers Needed to Treat is causing confusion about the scope for personalised medicine.

Stephen Senn
Consultant Statistician,


Thirty years ago, Laupacis et al1 proposed an intuitively appealing way that physicians could decide how to prioritise health care interventions: they could consider how many patients would need to be switched from an inferior treatment to a superior one in order for one to have an improved outcome. They called this the number needed to be treated. It is now more usually referred to as the number needed to treat (NNT).

Within fifteen years, NNTs were so well established that the then editor of the British Medical Journal, Richard Smith could write:  ‘Anybody familiar with the notion of “number needed to treat” (NNT) knows that it’s usually necessary to treat many patients in order for one to benefit’2. Fifteen years further on, bringing us up to date,  Wikipedia makes a similar point ‘The NNT is the average number of patients who need to be treated to prevent one additional bad outcome (e.g. the number of patients that need to be treated for one of them to benefit compared with a control in a clinical trial).’3

This common interpretation is false, as I have pointed out previously in two blogs on this site: Responder Despondency and  Painful Dichotomies. Nevertheless, it seems to me the point is worth making again and the thirty-year anniversary of NNTs provides a good excuse. Continue reading

Categories: personalized medicine, PhilStat/Med, S. Senn | 7 Comments

Statistics and the Higgs Discovery: 5-6 yr Memory Lane


I’m reblogging a few of the Higgs posts at the 6th anniversary of the 2012 discovery. (The first was in this post.) The following, was originally “Higgs Analysis and Statistical Flukes: part 2″ (from March, 2013).[1]

Some people say to me: “This kind of [severe testing] reasoning is fine for a ‘sexy science’ like high energy physics (HEP)”–as if their statistical inferences are radically different. But I maintain that this is the mode by which data are used in “uncertain” reasoning across the entire landscape of science and day-to-day learning (at least, when we’re trying to find things out)[2] Even with high level theories, the particular problems of learning from data are tackled piecemeal, in local inferences that afford error control. Granted, this statistical philosophy differs importantly from those that view the task as assigning comparative (or absolute) degrees-of-support/belief/plausibility to propositions, models, or theories.  Continue reading

Categories: Higgs, highly probable vs highly probed, P-values | 1 Comment

Replication Crises and the Statistics Wars: Hidden Controversies


Below are the slides from my June 14 presentation at the X-Phil conference on Reproducibility and Replicability in Psychology and Experimental Philosophy at University College London. What I think must be examined seriously are the “hidden” issues that are going unattended in replication research and related statistics wars. An overview of the “hidden controversies” are on slide #3. Although I was presenting them as “hidden”, I hoped they wouldn’t be quite as invisible as I found them through the conference. (Since my talk was at the start, I didn’t know what to expect–else I might have noted some examples that seemed to call for further scrutiny). Exceptions came largely (but not exclusively) from a small group of philosophers (me, Machery and Fletcher). Then again,there were parallel sessions, so I missed some.  However, I did learn something about X-phil, particularly from the very interesting poster session [1]. This new area should invite much, much more scrutiny of statistical methodology from philosophers of science.

[1] The women who organized and ran the conference did an excellent job: Lara Kirfel, a psychology PhD student at UCL, and Pascale Willemsen from Ruhr University.

Categories: Philosophy of Statistics, replication research, slides | Leave a comment

Your data-driven claims must still be probed severely

Vagelos Education Center

Below are the slides from my talk today at Columbia University at a session, Philosophy of Science and the New Paradigm of Data-Driven Science, at an American Statistical Association Conference on Statistical Learning and Data Science/Nonparametric Statistics. Todd was brave to sneak in philosophy of science in an otherwise highly mathematical conference.

Philosophy of Science and the New Paradigm of Data-Driven Science : (Room VEC 902/903)
Organizer and Chair: Todd Kuffner (Washington U)

  1. Deborah Mayo (Virginia Tech) “Your Data-Driven Claims Must Still be Probed Severely”
  2.  Ian McKeague (Columbia) “On the Replicability of Scientific Studies”
  3.  Xiao-Li Meng (Harvard) “Conducting Highly Principled Data Science: A Statistician’s Job and Joy


Categories: slides, Statistics and Data Science | 5 Comments

“Intentions (in your head)” is the code word for “error probabilities (of a procedure)”: Allan Birnbaum’s Birthday

27 May 1923-1 July 1976

27 May 1923-1 July 1976

Today is Allan Birnbaum’s Birthday. Birnbaum’s (1962) classic “On the Foundations of Statistical Inference,” in Breakthroughs in Statistics (volume I 1993), concerns a principle that remains at the heart of today’s controversies in statistics–even if it isn’t obvious at first: the Likelihood Principle (LP) (also called the strong likelihood Principle SLP, to distinguish it from the weak LP [1]). According to the LP/SLP, given the statistical model, the information from the data are fully contained in the likelihood ratio. Thus, properties of the sampling distribution of the test statistic vanish (as I put it in my slides from this post)! But error probabilities are all properties of the sampling distribution. Thus, embracing the LP (SLP) blocks our error statistician’s direct ways of taking into account “biasing selection effects” (slide #10). [Posted earlier here.] Interesting, as seen in a 2018 post on Neyman, Neyman did discuss this paper, but had an odd reaction that I’m not sure I understand. (Check it out.) Continue reading

Categories: Birnbaum, Birnbaum Brakes, frequentist/Bayesian, Likelihood Principle, phil/history of stat, Statistics | 7 Comments

The Meaning of My Title: Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars


Excerpts from the Preface:

The Statistics Wars: 

Today’s “statistics wars” are fascinating: They are at once ancient and up to the minute. They reflect disagreements on one of the deepest, oldest, philosophical questions: How do humans learn about the world despite threats of error due to incomplete and variable data? At the same time, they are the engine behind current controversies surrounding high-profile failures of replication in the social and biological sciences. How should the integrity of science be restored? Experts do not agree. This book pulls back the curtain on why. Continue reading

Categories: Announcement, SIST | 1 Comment

Getting Up to Speed on Principles of Statistics


“If a statistical analysis is clearly shown to be effective … it gains nothing from being … principled,” according to Terry Speed in an interesting IMS article (2016) that Harry Crane tweeted about a couple of days ago [i]. Crane objects that you need principles to determine if it is effective, else it “seems that a method is effective (a la Speed) if it gives the answer you want/expect.” I suspected that what Speed was objecting to was an appeal to “principles of inference” of the type to which Neyman objected in my recent post. This turns out to be correct. Here are some excerpts from Speed’s article (emphasis is mine): Continue reading

Categories: Likelihood Principle, Philosophy of Statistics | 5 Comments

3 YEARS AGO (May 2015): Monthly Memory Lane

3 years ago...               3 years ago…

MONTHLY MEMORY LANE: 3 years ago: May 2015. I mark in red 3-4 posts from each month that seem most apt for general background on key issues in this blog, excluding those reblogged recently[1]. Posts that are part of a “unit” or a group count as one, as in the case of 5/16, 5/19 and 5/24.

May 2015

  • 05/04 Spurious Correlations: Death by getting tangled in bedsheets and the consumption of cheese! (Aris Spanos)
  • 05/08 What really defies common sense (Msc kvetch on rejected posts)
  • 05/09 Stephen Senn: Double Jeopardy?: Judge Jeffreys Upholds the Law (sequel to the pathetic P-value)
  • 05/16 “Error statistical modeling and inference: Where methodology meets ontology” A. Spanos and D. Mayo
  • 05/19 Workshop on Replication in the Sciences: Society for Philosophy and Psychology: (2nd part of double header)
  • 05/24 From our “Philosophy of Statistics” session: APS 2015 convention
  • 05/27 “Intentions” is the new code word for “error probabilities”: Allan Birnbaum’s Birthday
  • 05/30 3 YEARS AGO (MAY 2012): Saturday Night Memory Lane

[1] Monthly memory lanes began at the blog’s 3-year anniversary in Sept, 2014.

I regret being away from blogging as of late (yes, the last bit of proofing on the book): I shall return soon! Send me stuff to post of yours or items of interest in the mean time.


Categories: 3-year memory lane | 1 Comment

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