Bad Statistics is Their Product: Fighting Fire With Fire (ii)

Posted on February 13, 2020 by Mayo

Mayo fights fire w/ fire

I. Doubt is Their Product is the title of a (2008) book by David Michaels, Assistant Secretary for OSHA from 2009-2017. I first mentioned it on this blog back in 2011 (“Will the Real Junk Science Please Stand Up?) The expression is from a statement by a cigarette executive (“doubt is our product”), and the book’s thesis is explained in its subtitle: How Industry’s Assault on Science Threatens Your Health. Imagine you have just picked up a book, published in 2020: Bad Statistics is Their Product. Is the author writing about how exaggerating bad statistics may serve in the interest of denying well-established risks? [Interpretation A]. Or perhaps she’s writing on how exaggerating bad statistics serves the interest of denying well-established statistical methods? [Interpretation B]. Both may result in distorting science and even in dismantling public health safeguards–especially if made the basis of evidence policies in agencies. A responsible philosopher of statistics should care.

II. Fixing Science. So, one day in January, I was invited to speak in a panel “Falsifiability and the Irreproducibility Crisis” at a conference “Fixing Science: Practical Solutions for the Irreproducibility Crisis.” The inviter, whom I did not know, David Randall, explained that a speaker withdrew from the session because of some kind of controversy surrounding the conference, but did not give details. He pointed me to an op-ed in the Wall Street Journal. I had already heard about the conference months before (from Nathan Schachtman) and before checking out the op-ed, my first thought was: I wonder if the controversy has to do with the fact that a keynote speaker is Ron Wasserstein, ASA Executive Director, a leading advocate of retiring “statistical significance”, and barring P-value thresholds in interpreting data. Another speaker eschews all current statistical inference methods (e.g., P-values, confidence intervals) as just too uncertain (D. Trafimow). More specifically, I imagined it might have to do with the controversy over whether the March 2019 editorial in TAS (Wasserstein, Schirm, and Lazar 2019) was a continuation of the ASA 2016 Statement on P-values, and thus an official ASA policy document, or not. Karen Kafadar, recent President of the American Statistical Association (ASA), made it clear in December 2019 that it is not.[2] The “no significance/no thresholds” view is the position of the guest editors of the March 2019 issue. (See “P-Value Statements and Their Unintended(?) Consequences” and “Les stats, c’est moi“.) Kafadar created a new 2020 ASA Task Force on Statistical Significance and Replicability to:

prepare a thoughtful and concise piece …without leaving the impression that p-values and hypothesis tests—and, perhaps by extension as many have inferred, statistical methods generally—have no role in “good statistical practice”. (Kafadar 2019, p. 4)

Maybe those inviting me didn’t know I’m “anti” the Anti-Statistical Significance campaign (“On some self-defeating aspects of the 2019 recommendations“), that  I agree with John Ioannidis (2019) that “retiring statistical significance would give bias a free pass“, and published an editorial “P-value Thresholds: Forfeit at Your Peril“. While I regard many of today’s statistical reforms as welcome (preregistration, testing for replication, transparency about data-dredging, P-hacking and multiple testing), I argue that those in Wasserstein et al., (2019) are “Doing more harm than good“. In “Don’t Say What You don’t Mean“, I express doubts that Wasserstein et al. (2019) could really mean to endorse certain statements in their editorial that are so extreme as to conflict with the ASA 2016 guide on P-values. To be clear, I reject oversimple dichotomies, and cookbook uses of tests, long lampooned, and have developed a reformulation of tests that avoids the fallacies of significance and non-significance.[1] It’s just that many of the criticisms are confused, and, consequently so are many reforms.

III. Bad Statistics is Their Product. It turns out that the brouhaha around the conference had nothing to do with all that. I thank Dorothy Bishop for pointing me to her blog which gives a much fuller background. Aside from the lack of women (I learned a new word–a manference), her real objection is on the order of “Bad Statistics is Their Product”: The groups sponsoring the Fixing Science conference, The National Association of Scholars and the Independent Institute, Bishop argues, are using the replication crisis to cast doubt on well-established risks, notably those of climate change. She refers to a book whose title echoes David Michael’s: Merchants of Doubt (2010) (by historians of science: Conway and Oreskes). Bishop writes:

Uncertainty about science that threatens big businesses has been promoted by think tanks … which receive substantial funding from those vested interests. The Fixing Science meeting has a clear overlap with those players. (Bishop)

The speakers on bad statistics, as she sees it, are “foils” for these interests, and thus “responsible scientists should avoid” the meeting.

But what if things are the reverse?  What if “bad statistics is our product” leaders also have an agenda. By influencing groups who have a voice in evidence policy in government agencies, they might effectively discredit methods they don’t like, and advance those they like. Suppose you have strong arguments that the consequences of this will undermine important safeguards (despite the key players being convinced they’re promoting better science). Then you should speak, if you can, and not stay away. You should try to fight fire with fire.

IV. So what Happened? So I accepted the invitation and gave what struck me as a fairly radical title: “P-Value ‘Reforms’: Fixing Science or Threats to Replication and Falsification?” (The abstract and slides are below.) Bishop is right that evidence of bad science can be exploited to selectively weaken entire areas of science; but evidence of bad statistics can also be exploited to selectively weaken entire methods one doesn’t like, and successfully gain acceptance of alternative methods, without the hard work of showing those alternative methods do a better, or even a good, job at the task at hand. Of course both of these things might be happening simultaneously.

Do the conference organizers overlap with science policy as Bishop alleges? I’d never encountered either outfits before, but Bishop quotes from their annual report.

In April we published The Irreproducibility Crisis, a report on the modern scientific crisis of reproducibility—the failure of a shocking amount of scientific research to discover true results because of slipshod use of statistics, groupthink, and flawed research techniques. We launched the report at the Rayburn House Office Building in Washington, DC; it was introduced by Representative Lamar Smith, the Chairman of the House Committee on Science, Space, and Technology.

So there is a mix with science policy makers in Washington, and their publication, The Irreproducibility Crisis, is clearly prepared to find its scapegoat in the bad statistics supposedly encouraged in statistical significance tests. To its credit, it discusses how data-dredging and multiple testing can make it easy to arrive at impressive-looking findings that are spurious, but nothing is said about ways to adjust or account for multiple testing and multiple modeling. (P-values are defined correctly, but their interpretation of confidence levels is incorrect.)  Published before the Wasserstein et al. (2019) call to end P-value thresholds, which would require the FDA and other agencies to end what many consider vital safeguards of error control, it doesn’t go that far. Not yet at least! Trying to prevent that from happening is a key reason I decided to attend. (updated 2/16)

My first step was to send David Randall my book, Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars (2018, CUP)–which he actually read and wrote a report on–and I met up with him in NYC to talk. He seemed surprised to learn about the controversies over statistical foundations and the disagreement about reforms. So did I hold people’s feet to the fire at the conference (when it came to scapegoating statistical significance tests and banning P-value thresholds for error probability control?) I did! I continue to do so in communications with David Randall. (I’ll write more in the comments to this post, once our slides are up.)

As for climate change, I wound up entirely missing that part of the conference: Due to the grounding of all flights to and from CLT the day I was to travel, thanks to rain, hail and tornadoes, I could only fly the following day, so our sessions were swapped. I hear the presentations will be posted. Doubtless, some people will use bad statistics and the “replication crisis” to claim there’s reason to reject our best climate change models, without having adequate knowledge of the science. But the real and present danger today that I worry about is that they will use bad statistics to claim there’s reason to reject our best (error) statistical practices, without adequate knowledge of the statistics or the philosophical and statistical controversies behind  the “reforms”.

Let me know what you think in the comments.

V. Here’s my abstract and slides

P-Value “Reforms”: Fixing Science or Threats to Replication and Falsification?

Mounting failures of replication give a new urgency to critically appraising proposed statistical reforms. While many reforms are welcome, others are quite radical. The sources of irreplication are not mysterious: in many fields, latitude in collecting and interpreting data makes it too easy to dredge up impressive looking findings even when spurious. Paradoxically, some of the reforms intended to fix science enable rather than reveal illicit inferences due to P-hacking, multiple testing, and data-dredging. Some even preclude testing and falsifying claims altogether. Too often the statistics wars become proxy battles between competing tribal leaders, each keen to advance a method or philosophy, rather than improve scientific accountability.

[1] Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars (SIST), 2018; SIST excerpts; Mayo and Cox 2006; Mayo and Spanos 2006.

[2] All uses of ASA II on this blog must now be qualified to reflect this.

[3] You can find a lot on the conference and the groups involved on-line. The letter by Lenny Teytelman warning people off the conference is here. Nathan Schachtman has a post up today on his law blog here.

 

Categories: ASA Guide to P-values, Error Statistics, P-values, replication research, slides | 25 Comments

My paper, “P values on Trial” is out in Harvard Data Science Review

Posted on February 1, 2020 by Mayo

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My new paper, “P Values on Trial: Selective Reporting of (Best Practice Guides Against) Selective Reporting” is out in Harvard Data Science Review (HDSR). HDSR describes itself as a A Microscopic, Telescopic, and Kaleidoscopic View of Data Science. The editor-in-chief is Xiao-li Meng, a statistician at Harvard. He writes a short blurb on each article in his opening editorial of the issue.

This is a case where reality proves the parody (or maybe, the proof of the parody is in the reality) or something like that. More specifically, Excursion 4 Tour III of my book Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars (2018, CUP) opens with a parody of a legal case, that of Scott Harkonen (in the parody, his name is Paul Hack). You can read it here. A few months after the book came out, the actual case took a turn that went even a bit beyond what I imagined could transpire in my parody. I got cold feet when it came to naming names in the book, but in this article I do.

Below I paste Meng’s blurb, followed by the start of my article.

Meng’s blurb (his full editorial is here):

P values on Trial (and the Beauty and Beast in a Single Number)

Perhaps there are no statistical concepts or methods that have been used and abused more frequently than statistical significance and the p value.  So much so that some journals are starting to recommend authors move away from rigid p value thresholds by which results are classified as significant or insignificant. The American Statistical Association (ASA) also issued a statement on statistical significance and p values in 2016, a unique practice in its nearly 180 years of history.  However, the 2016 ASA statement did not settle the matter, but only ignited further debate, as evidenced by the 2019 special issue of The American Statistician.  The fascinating account by the eminent philosopher of science Deborah Mayo of how the ASA’s 2016 statement was used in a legal trial should remind all data scientists that what we do or say can have completely unintended consequences, despite our best intentions.

The ASA is a leading professional society of the studies of uncertainty and variabilities. Therefore, the tone and overall approach of its 2016 statement is understandably nuanced and replete with cautionary notes. However, in the case of Scott Harkonen (CEO of InterMune), who was found guilty of misleading the public by reporting a cherry-picked ‘significant p value’ to market the drug Actimmune for unapproved uses, the appeal lawyers cited the ASA Statement’s cautionary note that “a p value without context or other evidence provides limited information,” as compelling new evidence that the scientific theory upon which petitioner’s conviction was based [that of statistical significance testing] is demonstrably false.  I doubt the authors of the ASA statement ever anticipated that their warning against the inappropriate use of p value could be turned into arguments for protecting exactly such uses.

To further clarify the ASA’s position, especially in view of some confusions generated by the aforementioned special issue, the ASA recently established a task force on statistical significance (and research replicability) to “develop thoughtful principles and practices that the ASA can endorse and share with scientists and journal editors” within 2020.  As a member of the task force, I’m particularly mindful of the message from Mayo’s article, and of the essentially impossible task of summarizing scientific evidence by a single number.  As consumers of information, we are all seduced by simplicity, and nothing is simpler than conveying everything through a single number, which renders simplicity on multiple fronts, from communication to decision making.  But, again, there is no free lunch.  Most problems are just too complex to be summarized by a single number, and concision in this context can exact a considerable cost. The cost could be a great loss of information or validity of the conclusion, which are the central concerns regarding the p value.  The cost can also be registered in terms of the tremendous amount of hard work it may take to produce a usable single summary.

P-Values on Trial: Selective Reporting of (Best Practice Guides Against) Selective Reporting

Abstract

In an attempt to stem the practice of reporting impressive-looking findings based on data dredging and multiple testing, the American Statistical Association’s (ASA) 2016 guide to interpreting p values (Wasserstein & Lazar) warns that engaging in such practices “renders the reported p-values essentially uninterpretable” (pp. 131-132). Yet some argue that the ASA statement actually frees researchers from culpability for failing to report or adjust for data dredging and multiple testing. We illustrate the puzzle by means of a case appealed to the Supreme Court of the United States: that of Scott Harkonen. In 2009, Harkonen was found guilty of issuing a misleading press report on results of a drug advanced by the company of which he was CEO. Downplaying the high p value on the primary endpoint (and 10 secondary points), he reported statistically significant drug benefits had been shown, without mentioning this referred only to a subgroup he identified from ransacking the unblinded data. Nevertheless, Harkonen and his defenders argued that “the conclusions from the ASA Principles are the opposite of the government’s” conclusion that his construal of the data was misleading (Harkonen v. United States, 2018, p. 16). On the face of it, his defenders are selectively reporting on the ASA guide, leaving out its objections to data dredging. However, the ASA guide also points to alternative accounts to which some researchers turn to avoid problems of data dredging and multiple testing. Since some of these accounts give a green light to Harkonen’s construal, a case might be made that the guide, inadvertently or not, frees him from culpability.

Keywords: statistical significance, p values, data dredging, multiple testing, ASA guide to p values, selective reporting

  1. Introduction

The biggest source of handwringing about statistical inference boils down to the fact it has become very easy to infer claims that have not been subjected to stringent tests. Sifting through reams of data makes it easy to find impressive-looking associations, even if they are spurious. Concern with spurious findings is considered sufficiently serious to have motivated the American Statistical Association (ASA) to issue a guide to stem misinterpretations of p values (Wasserstein & Lazar, 2016; hereafter, ASA guide). Principle 4 of the ASA guide asserts that:

Proper inference requires full reporting and transparency. P-values and related analyses should not be reported selectively. Conducting multiple analyses of the data and reporting only those with certain p-values (typically those passing a significance threshold) renders the reported p-values essentially uninterpretable. (pp. 131–132)

An intriguing example is offered by a legal case that was back in the news in 2018, having made it to the U.S. Supreme Court (Harkonen v. United States, 2018). In 2009, Scott Harkonen (CEO of drug company InterMune) was found guilty of wire fraud for issuing a misleading press report on Phase III results of a drug Actimmune in 2002, successfully pumping up its sales. While Actimmune had already been approved for two rare diseases, it was hoped that the FDA would approve it for a far more prevalent, yet fatal, lung disease (whose treatment would cost patients $50,000 a year). Confronted with a disappointing lack of statistical significance (p = .52)[1] on the primary endpoint—that the drug improves lung function as reflected by progression free survival—and on any of ten prespecified endpoints, Harkonen engaged in postdata dredging on the unblinded data until he unearthed a non-prespecified subgroup with a nominally statistically significant survival benefit. The day after the Food and Drug Administration (FDA) informed him it would not approve the use of the drug on the basis of his post hoc finding, Harkonen issued a press release to doctors and shareholders optimistically reporting Actimmune’s statistically significant survival benefits in the subgroup he identified from ransacking the unblinded data.

What makes the case intriguing is not its offering yet another case of p-hacking, nor that it has found its way more than once to the Supreme Court. Rather, it is because in 2018, Harkonen and his defenders argued that the ASA guide provides “compelling new evidence that the scientific theory upon which petitioner’s conviction was based [that of statistical significance testing] is demonstrably false” (Goodman, 2018, p. 3). His appeal alleges that “the conclusions from the ASA Principles are the opposite of the government’s” charge that his construal of the data was misleading (Harkonen v. United States, 2018, p. 16 ).

Are his defenders merely selectively reporting on the ASA guide, making no mention of Principle 4, with its loud objections to the behavior Harkonen displayed? It is hard to see how one can hold Principle 4 while averring the guide’s principles run counter to the government’s charges against Harkonen. However, if we view the ASA guide in the context of today’s disputes about statistical evidence, things may look topsy turvy. None of the attempts to overturn his conviction succeeded (his sentence had been to a period of house arrest and a fine), but his defenders are given a leg to stand on—wobbly as it is. While the ASA guide does not show that the theory of statistical significance testing ‘is demonstrably false,’ it might be seen to communicate a message that is in tension with itself on one of the most important issues of statistical inference.

Before beginning, some caveats are in order. The legal case was not about which statistical tools to use, but merely whether Harkonen, in his role as CEO, was guilty of intentionally issuing a misleading report to shareholders and doctors. However, clearly, there could be no hint of wrongdoing if it were acceptable to treat post hoc subgroups the same as prespecified endpoints. In order to focus solely on that issue, I put to one side the question whether his press report rises to the level of wire fraud. Lawyer Nathan Schachtman argues that “the judgment in United States v. Harkonen is at odds with the latitude afforded companies in securities fraud cases” even where multiple testing occurs (Schachtman, 2020, p. 48). Not only are the intricacies of legal precedent outside my expertise, the arguments in his defense, at least the ones of interest here, regard only the data interpretation. Moreover, our concern is strictly with whether the ASA guide provides grounds to exonerate Harkonen-like interpretations of data.

I will begin by describing the case in relation to the ASA guide. I then make the case that Harkonen’s defenders mislead by omission of the relevant principle in the guide. I will then reopen my case by revealing statements in the guide that have thus far been omitted from my own analysis. Whether they exonerate Harkonen’s defenders is for you, the jury, to decide.

You can read the full article at HDSR here. The Harkonen case is also discussed on this blog: search Harkonen (and Matrixx).

 

Categories: multiple testing, P-values, significance tests, Statistics | 29 Comments

S. Senn: “Error point: The importance of knowing how much you don’t know” (guest post)

Posted on January 20, 2020 by Mayo

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Stephen Senn
Consultant Statistician
Edinburgh

‘The term “point estimation” made Fisher nervous, because he associated it with estimation without regard to accuracy, which he regarded as ridiculous.’ Jimmy Savage [1, p. 453] 

First things second

The classic text by David Cox and David Hinkley, Theoretical Statistics (1974), has two extremely interesting features as regards estimation. The first is in the form of an indirect, implicit, message and the second explicit and both teach that point estimation is far from being an obvious goal of statistical inference. The indirect message is that the chapter on point estimation (chapter 8) comes after that on interval estimation (chapter 7). This may puzzle the reader, who may anticipate that the complications of interval estimation would be handled after the apparently simpler point estimation rather than before. However, with the start of chapter 8, the reasoning is made clear. Cox and Hinkley state:

Superficially, point estimation may seem a simpler problem to discuss than that of interval estimation; in fact, however, any replacement of an uncertain quantity is bound to involve either some arbitrary choice or a precise specification of the purpose for which the single quantity  is required. Note that in interval-estimation we explicitly recognize that the conclusion is uncertain, whereas in point estimation…no explicit recognition is involved in the final answer. [2, p. 250]

In my opinion, a great deal of confusion about statistics can be traced to the fact that the point estimate is seen as being the be all and end all, the expression of uncertainty being forgotten. For example, much of the criticism of randomisation overlooks the fact that the statistical analysis will deliver a probability statement and, other things being equal, the more unobserved prognostic factors there are, the more uncertain the result will be claimed to be. However, statistical statements are not wrong because they are uncertain, they are wrong if claimed to be more certain (or less certain) than they are. Continue reading →

Categories: Fisher, randomization, Stephen Senn | Tags: | 7 Comments

Aris Spanos Reviews Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars

Posted on January 11, 2020 by Mayo

A. Spanos

Aris Spanos was asked to review my Statistical Inference as Severe Testing: how to Get Beyond the Statistics Wars (CUP, 2018), but he was to combine it with a review of the re-issue of Ian Hacking’s classic  Logic of Statistical Inference. The journal is OEconomia: History, Methodology, Philosophy. Below are excerpts from his discussion of my book (pp. 843-860). I will jump past the Hacking review, and occasionally excerpt for length.To read his full article go to external journal pdf or stable internal blog pdf.

….

2 Mayo (2018). Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars

The sub-title of Mayo’s (2018) book provides an apt description of the primary aim of the book in the sense that its focus is on the current discussions pertaining to replicability and trustworthy empirical evidence that revolve around the main fault line in statistical inference: the nature, interpretation and uses of probability in statistical modeling and inference. This underlies not only the form and structure of inductive inference, but also the nature of the underlying statistical reasonings as well as the nature of the evidence it gives rise to. Continue reading →

Categories: Spanos, Statistical Inference as Severe Testing | Leave a comment

The NAS fixes its (main) mistake in defining P-values!

Posted on January 7, 2020 by Mayo
Mayo new elbow

(reasonably) satisfied

Remember when I wrote to the National Academy of Science (NAS) in September pointing out mistaken definitions of P-values in their document on Reproducibility and Replicability in Science? (see my 9/30/19 post). I’d given up on their taking any action, but yesterday I received a letter from the NAS Senior Program officer:

Dear Dr. Mayo,

I am writing to let you know that the Reproducibility and Replicability in Science report has been updated in response to the issues that you have raised.
Two footnotes, on pages 31 35 and 221, highlight the changes. The updated report is available from the following link: NEW 2020 NAS DOC

Thank you for taking the time to reach out to me and to Dr. Fineberg and letting us know about your concerns.
With kind regards and wishes of a happy 2020,
Jenny Heimberg
Jennifer Heimberg, Ph.D.
Senior Program Officer

The National Academies of Sciences, Engineering, and Medicine

Continue reading →

Categories: NAS, P-values | 2 Comments

Midnight With Birnbaum (Happy New Year 2019)!

Posted on December 31, 2019 by Mayo

 Just as in the past 8 years since I’ve been blogging, I revisit that spot in the road at 9p.m., just outside the Elbar Room, look to get into a strange-looking taxi, to head to “Midnight With Birnbaum”. (The pic on the left is the only blurry image I have of the club I’m taken to.) I wonder if the car will come for me this year, as I wait out in the cold, now that Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars (STINT 2018) has been out over a year. STINT doesn’t rehearse the argument from my Birnbaum article, but there’s much in it that I’d like to discuss with him. The (Strong) Likelihood Principle–whether or not it is named–remains at the heart of many of the criticisms of Neyman-Pearson (N-P) statistics (and cognate methods). 2019 was the 61th birthday of Cox’s “weighing machine” example, which was the basis of Birnbaum’s attempted proof. Yet as Birnbaum insisted, the “confidence concept” is the “one rock in a shifting scene” of statistical foundations, insofar as there’s interest in controlling the frequency of erroneous interpretations of data. (See my rejoinder.) Birnbaum bemoaned the lack of an explicit evidential interpretation of N-P methods. Maybe in 2020? Anyway, the cab is finally here…the rest is live. Happy New Year! Continue reading →

Categories: Birnbaum Brakes, strong likelihood principle | Tags: , , , | Leave a comment

A Perfect Time to Binge Read the (Strong) Likelihood Principle

Posted on December 30, 2019 by Mayo

An essential component of inference based on familiar frequentist notions: p-values, significance and confidence levels, is the relevant sampling distribution (hence the term sampling theory, or my preferred error statistics, as we get error probabilities from the sampling distribution). This feature results in violations of a principle known as the strong likelihood principle (SLP). To state the SLP roughly, it asserts that all the evidential import in the data (for parametric inference within a model) resides in the likelihoods. If accepted, it would render error probabilities irrelevant post data. Continue reading →

Categories: Birnbaum, Birnbaum Brakes, law of likelihood | 7 Comments

61 Years of Cox’s (1958) Chestnut: Excerpt from Excursion 3 Tour II (Mayo 2018, CUP)

Posted on December 30, 2019 by Mayo

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2018 marked 60 years since the famous weighing machine example from Sir David Cox (1958)[1]. it is now 61. It’s one of the “chestnuts” in the exhibits of “chestnuts and howlers” in Excursion 3 (Tour II) of my (still) new book Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars (SIST, 2018). It’s especially relevant to take this up now, just before we leave 2019, for reasons that will be revealed over the next day or two. For a sneak preview of those reasons, see the “note to the reader” at the end of this post. So, let’s go back to it, with an excerpt from SIST (pp. 170-173). Continue reading →

Categories: Birnbaum, Statistical Inference as Severe Testing, strong likelihood principle | Leave a comment

Posts of Christmas Past (1): 13 howlers of significance tests (and how to avoid them)

Posted on December 24, 2019 by Mayo

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I’m reblogging a post from Christmas past–exactly 7 years ago. Guess what I gave as the number 1 (of 13) howler well-worn criticism of statistical significance tests, haunting us back in 2012–all of which are put to rest in Mayo and Spanos 2011? Yes, it’s the frightening allegation that statistical significance tests forbid using any background knowledge! The researcher is imagined to start with a “blank slate” in each inquiry (no memories of fallacies past), and then unthinkingly apply a purely formal, automatic, accept-reject machine. What’s newly frightening (in 2019) is the credulity with which this apparition is now being met (by some). I make some new remarks below the post from Christmas past: Continue reading →

Categories: memory lane, significance tests, Statistics | Tags: | Leave a comment

“Les stats, c’est moi”: We take that step here! (Adopt our fav word or phil stat!)(iii)

Posted on December 13, 2019 by Mayo

les stats, c’est moi

When it comes to the statistics wars, leaders of rival tribes sometimes sound as if they believed “les stats, c’est moi”.  [1]. So, rather than say they would like to supplement some well-known tenets (e.g., “a statistically significant effect may not be substantively important”) with a new rule that advances their particular preferred language or statistical philosophy, they may simply blurt out: “we take that step here!” followed by whatever rule of language or statistical philosophy they happen to prefer (as if they have just added the new rule to the existing, uncontested tenets). Karan Kefadar, in her last official (December) report as President of the American Statistical Association (ASA), expresses her determination to call out this problem at the ASA itself. (She raised it first in her June article, discussed in my last post.) Continue reading →

Categories: ASA Guide to P-values | 84 Comments

P-Value Statements and Their Unintended(?) Consequences: The June 2019 ASA President’s Corner (b)

Posted on November 30, 2019 by Mayo
2208388671_0d8bc38714

Mayo writing to Kafadar

I never met Karen Kafadar, the 2019 President of the American Statistical Association (ASA), but the other day I wrote to her in response to a call in her extremely interesting June 2019 President’s Corner: “Statistics and Unintended Consequences“:

  • “I welcome your suggestions for how we can communicate the importance of statistical inference and the proper interpretation of p-values to our scientific partners and science journal editors in a way they will understand and appreciate and can use with confidence and comfort—before they change their policies and abandon statistics altogether.”

I only recently came across her call, and I will share my letter below. First, here are some excerpts from her June President’s Corner (her December report is due any day). Continue reading →

Categories: ASA Guide to P-values, Bayesian/frequentist, P-values | 3 Comments

A. Saltelli (Guest post): What can we learn from the debate on statistical significance?

Posted on November 22, 2019 by Mayo

Professor Andrea Saltelli
Centre for the Study of the Sciences and the Humanities (SVT), University of Bergen (UIB, Norway),
&
Open Evidence Research, Universitat Oberta de Catalunya (UOC), Barcelona

What can we learn from the debate on statistical significance?

The statistical community is in the midst of crisis whose latest convulsion is a petition to abolish the concept of significance. The problem is perhaps neither with significance, nor with statistics, but with the inconsiderate way we use numbers, and with our present approach to quantification.  Unless the crisis is resolved, there will be a loss of consensus in scientific arguments, with a corresponding decline of public trust in the findings of science. Continue reading →

Categories: Error Statistics | 11 Comments

The ASA’s P-value Project: Why it’s Doing More Harm than Good (cont from 11/4/19)

Posted on November 14, 2019 by Mayo

 

cure by committee

Everything is impeach and remove these days! Should that hold also for the concept of statistical significance and P-value thresholds? There’s an active campaign that says yes, but I aver it is doing more harm than good. In my last post, I said I would count the ways it is detrimental until I became “too disconsolate to continue”. There I showed why the new movement, launched by Executive Director of the ASA (American Statistical Association), Ronald Wasserstein (in what I dub ASA II), is self-defeating: it instantiates and encourages the human-all-too-human tendency to exploit researcher flexibility, rewards, and openings for bias in research (F, R & B Hypothesis). That was reason #1. Just reviewing it already fills me with such dismay, that I fear I will become too disconsolate to continue before even getting to reason #2. So let me just quickly jot down reasons #2, 3, 4, and 5 (without full arguments) before I expire. Continue reading →

Categories: ASA Guide to P-values | 7 Comments

On Some Self-Defeating Aspects of the ASA’s (2019) Recommendations on Statistical Significance Tests (ii)

Posted on November 4, 2019 by Mayo

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“Before we stood on the edge of the precipice, now we have taken a great step forward”

 

What’s self-defeating about pursuing statistical reforms in the manner taken by the American Statistical Association (ASA) in 2019? In case you’re not up on the latest in significance testing wars, the 2016 ASA Statement on P-Values and Statistical Significance, ASA I, arguably, was a reasonably consensual statement on the need to avoid some well-known abuses of P-values–notably if you compute P-values, ignoring selective reporting, multiple testing, or stopping when the data look good, the computed P-value will be invalid. (Principle 4, ASA I) But then Ron Wasserstein, executive director of the ASA, and co-editors, decided they weren’t happy with their own 2016 statement because it “stopped just short of recommending that declarations of ‘statistical significance’ be abandoned” altogether. In their new statement–ASA II–they announced: “We take that step here….Statistically significant –don’t say it and don’t use it”.

Why do I say it is a mis-take to have taken the supposed next “great step forward”? Why do I count it as unsuccessful as a piece of statistical science policy? In what ways does it make the situation worse? Let me count the ways. The first is in this post. Others will come in following posts, until I become too disconsolate to continue.[i] Continue reading →

Categories: P-values, stat wars and their casualties, statistical significance tests | 14 Comments

Exploring a new philosophy of statistics field

Posted on October 30, 2019 by Mayo

This article came out on Monday on our Summer Seminar in Philosophy of Statistics in Virginia Tech News Daily magazine.

October 28, 2019

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From universities around the world, participants in a summer session gathered to discuss the merits of the philosophy of statistics. Co-director Deborah Mayo, left, hosted an evening for them at her home.

Continue reading →

Categories: Philosophy of Statistics, Summer Seminar in PhilStat | 2 Comments

The First Eye-Opener: Error Probing Tools vs Logics of Evidence (Excursion 1 Tour II)

Posted on October 21, 2019 by Mayo

1.4, 1.5

In Tour II of this first Excursion of Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars (SIST, 2018, CUP),  I pull back the cover on disagreements between experts charged with restoring integrity to today’s statistical practice. Some advised me to wait until later (in the book) to get to this eye-opener. Granted, the full story involves some technical issues, but after many months, I think I arrived at a way to get to the heart of things informally (with a promise of more detailed retracing of steps later on). It was too important not to reveal right away that some of the most popular “reforms” fall down on the job even with respect to our most minimal principle of evidence (you don’t have evidence for a claim if little if anything has been done to probe the ways it can be flawed).  Continue reading →

Categories: Error Statistics, law of likelihood, SIST | 14 Comments

The Current State of Play in Statistical Foundations: A View From a Hot-Air Balloon

Posted on October 15, 2019 by Mayo

1.3

Continue to the third, and last stop of Excursion 1 Tour I of Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars (2018, CUP)–Section 1.3. It would be of interest to ponder if (and how) the current state of play in the stat wars has shifted in just one year. I’ll do so in the comments. Use that space to ask me any questions.

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)

Continue reading →

Categories: Statistical Inference as Severe Testing | 3 Comments

Severity: Strong vs Weak (Excursion 1 continues)

Posted on October 10, 2019 by Mayo

1.2

Marking one year since the appearance of my book: Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars (2018, CUP), let’s continue to the second stop (1.2) of Excursion 1 Tour 1. It begins on p. 13 with a quote from statistician George Barnard. Assorted reflections will be given in the comments. Ask me any questions pertaining to the Tour.

 

  • 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)

Continue reading →

Categories: Statistical Inference as Severe Testing | 5 Comments

How My Book Begins: Beyond Probabilism and Performance: Severity Requirement

Posted on October 8, 2019 by Mayo

This week marks one year since the general availability of my book: Statistical Inference as Severe Testing: How to Get Beyond the Statistics Wars (2018, CUP). Here’s how it begins (Excursion 1 Tour 1 (1.1)). Material from the preface is here. I will sporadically give some “one year later” reflections in the comments. I invite readers to ask me any questions pertaining to the Tour.

The journey begins..(1.1)

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.

Continue reading →

Categories: Statistical Inference as Severe Testing, Statistics | 4 Comments

National Academies of Science: Please Correct Your Definitions of P-values

Posted on September 30, 2019 by Mayo

Mayo banging head

If you were on a committee to highlight issues surrounding P-values and replication, what’s the first definition you would check? Yes, exactly. Apparently, when it came to the recently released National Academies of Science “Consensus Study” Reproducibility and Replicability in Science 2019, no one did. Continue reading →

Categories: ASA Guide to P-values, Error Statistics, P-values | 20 Comments

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