Peer Review, PubPeer, PubChase, and Rule 702 – Candles in the Ear

In deciding the Daubert case, the Supreme Court identified several factors to assess whether “the reasoning or methodology underlying the testimony is scientifically valid and of whether that reasoning or methodology properly can be applied to the facts in issue.” One of those factors was whether the proffered opinion had been “peer reviewed” and published. Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 593-94 (1993). The Court explained the publication factor:

“Another pertinent consideration is whether the theory or technique has been subjected to peer review and publication. Publication (which is but one element of peer review) is not a sine qua non of admissibility; it does not necessarily correlate with reliability, and in some instances well-grounded but innovative theories will not have been published. Some propositions, moreover, are too particular, too new, or of too limited interest to be published. But submission to the scrutiny of the scientific community is a component of ‘good science,’ in part because it increases the likelihood that substantive flaws in methodology will be detected. The fact of publication (or lack thereof) in a peer reviewed journal thus will be a relevant, though not dispositive, consideration in assessing the scientific validity of a particular technique or methodology on which an opinion is premised.”

Daubert, 509 U.S. at 593-94 (internal citations omitted). See, e.g., Lust v. Merrell Dow Pharms., Inc., 89 F. 3d 594, 597 (9th Cir. 1996) (affirming exclusion of Dr. Alan Done, plaintiffs’ expert witness in Chlomid birth defects case, in part because of the lack of peer review and publication of his litigation-driven opinions); Hall v. Baxter Healthcare Corp., 947 F. Supp. 1387, 1406 (1996)  (noting that “the lack of peer review for [epidemiologist] Dr. Swan’s theories weighs heavily against the admissibility of Dr. Swan’s testimony”).

Case law since Daubert has made clear that peer review is neither necessary nor sufficient for the admissibility of an opinion. United States v. Mikos, 539 F.3d 706, 711 (7th Cir. 2008) (noting that the absence of peer-reviewed studies on subject of bullet grooving did not render opinion, based upon FBI database, inadmissible); In re Zoloft Prods. Liab. Litig. MDL No. 2342; 12-md-2342,  2014 U.S. Dist. LEXIS 87592; 2014 WL 2921648 (E.D. Pa. June 27, 2014) (excluding proffered testimony of epidemiologist Anick Bérard for arbitrarily selecting some point estimates and ignoring others in published studies).

As Susan Haack has noted, “peer review” has taken on mythic proportions in the adjudication of expert witness opinion admissibility.  Susan Haack, “Peer Review and Publication: Lessons for Lawyers,” 36 Stetson L. Rev. 789 (2007), republished in Susan Haack, Evidence Matters: Science, Proof, and Truth in the Law 156 (2014). Peer review, at best, is a weak proxy for the study validity, which is what is really needed in judicial proceedings. Proxies avoid the labor of independent, original thought, and so they are much favored by many judges.

In the past, some litigants oversold peer review as a touchstone of reliable, admissible expert witness testimony only to find that some very shoddy opinions show up in ostensibly peer-reviewed journals. SeeMisplaced Reliance On Peer Review to Separate Valid Science From Nonsense” (Aug. 14, 2011). Scientists often claim that science is “self-correcting,” but in some areas of research, there are few severe tests and little critical review, and mostly glib confirmations from acolytes.

Letters to the editor are sometimes held out as a remedy to peer-review screw ups, but such letters, which are not themselves peer reviewed, are subject to the whims of imperious editors who might wish to silence the views of those who would be critical of their judgment in publishing the article under discussion. Most journals have space only for a few letters, and unpopular but salient points of view can go unreported. Many scientists will not write letters to the editors, even when the published article is terribly wrong in its methods, data analyses, conclusions, or discussion.  Letters to the editor are often frowned upon in academic circles as not advancing affirmative research and scholarship agenda.

Letters to the editor often must be sent within a short time window of initial publication, often too short for busy academics to analyze a paper carefully and comment.  Furthermore, letters  and are often limited to a few hundred words, which length is often inadequate to develop a careful critique or exposition of the issues in the paper.  Moreover, such letters suffer from an additional procedural problem:  authors are permitted a response, and the letter writers are not permitted a reply. Authors thus get the last word, which they can often use to deflect or diffuse important criticisms.  The authors’ response can be sufficiently self-serving and misleading, with immunity from further criticism, that many would-be correspondents abandon the project altogether. See, e.g., PubPeer – “Example case showing why letters to the editor can be a waste of time” (Oct. 8, 2013).

Websites and blogs provide for dynamic content, with the potential for critical reviews that can be identified by search engines. See, e.g., Paul S. Brookes, “Our broken academic journal corrections system,” PSBLAB: Cardiac Mitochondrial Research in the Lab (Jan. 14, 2014). Mostly, the internet holds untapped potential for analysis, discussion, and debate on published studies.  To be sure, some journals provide “comment fields,” on their websites, with an opportunity for open discussion.  Often, full critiques must be developed and presented elsewhere. See, e.g., Androgen Study Group, “Letter to JAMA Asking for Retraction of Misleading Article on Testosterone Therapy” (Mar. 25, 2014).


Kate Yandell, in TheScientist, reports on the creation of PubPeer a few years ago, as a forum for post-publication review and discussion published scientific papers. Kate Yandell, “Concerns Raised Online Linger” (Aug. 25, 2014).  Billing itself as an “online journal club,” PubPeer has pointed out potentially serious problems, some of which have led to retractions and corrections. Another internet site of interest is PubChase, which monitors discussion of particular articles, as well as generating email alerts and recommendations for related articles.

One journal editor has taken notice and given notice that he will not pay attention to post-publication peer review.  Eric J. Murphy, the editor in chief of Lipids, posting a comment at PubPeer, illustrates that there will be a good deal of resistance to post-publication open peer review, out of the control of journal editors:

“As an Editor-in-Chief of a society journal, I have never examined PubPeer nor will I do so. First, there is the crowd or group mentality that may over emphasize some point in an irrational manner.  Just as using the marble theory of officiating is bad, one should never base a decision on the quantity of negative or positive comments. Second, if the concerned individual sent an e-mail or letter to me, then I would be duty bound to examine the issue.  It is not my duty to monitor PubPeer or any other such site, but rather to respond to queries sent to me.  So, with regards to Hugh’s point, I don’t support that position at all.

Mistakes happen, although frankly we try to limit these mistakes and do take steps to prevent publishing papers with FFP, it does happen.  Also, honest mistakes happen in science all the time, so[me] of these result in an erratum, while others go unnoticed by editors and reviewers.  In such a case, someone who does notice should contact the editor to put them on notice regarding the issue so that it may be resolved.  Resolution does not necessarily mean correction, but rather the editor taking a close look at the situation, discussing the situation with the original authors, and then reaching a decision.  Most of the time a correction will be made, but not always.”

Murphy’s comments are remarkable.  PubPeer provides a forum for post-publication comment, but it hardly requires editors, investigators, and consumers of scientific studies to evaluate published works by “nose counts” of favorable and unfavorable comments.  This is not, and never has been, a democratic enterprise.  Somehow, we might expect Murphy and others to evaluate the comments, on the merits, not on their prevalence.  Murphy’s declaration that he is duty-bound to investigate and evaluate letters or emails sent to him about published articles is encouraging, but the editors’ ability to ratify publication, in the face of a private communication, without comment to the scientific community, strips the community of making a principled decision on its own.  Murphy’s way, which seems largely the way of contemporary scientific publishing, ignores the important social dimension of scientific debate and resolution of issues.  Leaving control of the discussion in the hands of the editors who approved and published studies may be asking too much of editors. Nemo iudex in causa sua.

PubPeer has already tested the limits of free speech. Kate Yandell, “PubPeer Threatened with Legal Action” (Aug. 19, 2014). A scientist whose works were receiving unfavorable attention on PubPeer threatened a lawsuit.  Let’s hope that scientists can learn to be sufficiently thick skinned that there can be open discourse of the merits of their research, their data, and their conclusions.

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