It all started with a press conference on March 17th, 2014. Leaders of the BICEP2 team claimed that they found the “first direct evidence of cosmic inflation”, and the “first images of gravitational waves, or ripples in space-time.” This is a huge advance in cosmology if true. The publicity occurred before the paper was accepted for publication in a journal, and the work has been cross-examined by experts ever since. For excellent summaries of the initial claim and the skeptical response by some scientists, see articles by Richard Easther, Alan Duffy and Heino Falcke. The article by Falcke is particularly interesting because he discusses science communication issues raised by this story.
In this blog post I will add to Falcke’s comments by discussing some of the pros and cons of publicizing a paper before it is accepted, using the BICEP2 result as a case study. I note that the BICEP2 paper has just been published in Physical Review Letters and includes a few substantial changes and some hedging on the original claims, as reported by Dennis Overbye in the New York Times, Jacob Aron, Lisa Grossman and Stuart Clark in New Scientist and Nadia Drake in National Geographic News.
|Gravitational waves from inflation are expected to generate a faint but distinctive twisting pattern in the polarization of the cosmic microwave background (CMB), the left over radiation from the Big Bang. This twisting pattern is known as a "curl" or B-mode pattern. For the density fluctuations that generate most of the polarization of the CMB, this part of the primordial pattern is exactly zero. Shown here is the actual B-mode pattern observed with the BICEP2 telescope, which is consistent with the pattern predicted for primordial gravitational waves. The line segments show the polarization strength and orientation at different spots on the sky. The red and blue shading shows the degree of clockwise and anti-clockwise twisting of this B-mode pattern. (Caption has been slightly modified from the CfA version.) Credit: BICEP2 collaboration|
(In full disclosure, I work in public affairs in the Chandra X-ray Center based at the Harvard-Smithsonian Center for Astrophysics, where the BICEP2 results were announced and where part of the BICEP2 team is based, but I don’t know any of the team members personally. Also, unless noted otherwise, I will use the term “peer review” in the traditional sense, to describe independent review conducted by a referee or referees selected by a journal’s editors as part of their publication process.)
What are some of the advantages of doing publicity before a paper is accepted to a journal?
− Peer review is not a flawless process and this is a public way to acknowledge that. As biologist and blogger Jonathan Eisen has pointed out, we should not deify peer review. There are many examples where peer review has failed to detect serious problems published in science papers, including the well-known "arsenic life" paper in Science. This article by Carl Zimmer gave a devastating response to that paper by independent experts, not long after it was published, contrasting strongly with the very positive reviews by referees, as reported by Dan Vergano.
One of the problems caused by the arsenic paper was that multiple scientific disciplines were covered, making the paper difficult to referee, even using three reviewers. In astrophysics, most of the commonly-used journals like The Astrophysical Journal usually use only one referee, so if the journal makes a poor choice of referee, the review can have very limited benefits. However, with BICEP2 a much more narrow range of expertise was required than for the arsenic paper, and there was an obvious choice for a referee: one of the leading researchers for WMAP or Planck would have been very appropriate. In their published paper, the authors acknowledge “detailed and constructive recommendations” from two anonymous referees.
− In cases where peer review has failed we can thank post-publication peer review for exposing the problems. By publicizing before peer review, authors are effectively inviting an open, informal refereeing process to run in parallel with the journal’s peer review. The BICEP2 authors effectively acknowledge this in the “Note added” section near the end of their published paper. An open process like this gives scrutiny from the greatest possible number of experts before the paper is published. Such an approach makes a lot of sense in giving the best paper, assuming that the authors seriously consider the comments they receive, as the BICEP2 authors appear to have done. (As an aside, open peer review arguably should include a public record of comments and responses, as suggested, for example, by planners of the Open Journal for Astrophysics. However, this journal is still in the testing phase.)
Similarly − on the publicity side − much of the potential benefit of open peer review depends on how the team respond to external comments and criticism. For example, if necessary, will they put out a new release or a correction explaining any changes to their original publicity claims, especially when more data becomes available?
− By placing the paper on the arXiv and publicizing it at an early stage, there is an opportunity for outsiders to witness some of the scientific process in action, as noted by Dennis Overbye. In the case of BICEP2 the skepticism of experts was quickly revealed in comments given in the press, as reported by Joel Achenbach. The paper triggered a flurry of activity, with 421 papers citing the original paper − at the time of writing − most of them theory papers where the result was assumed to be correct. At the same time, the detailed observational results were closely examined and criticized as noted by Richard Easther, Alan Duffy, Heino Falcke and others, resulting in some important revisions.
− By doing publicity before publication, results can be released to the public and to other scientists earlier than they otherwise would have been, since the authors do not have to wait for the refereeing process. In fields like medical science, delays can potentially be life-threatening. In astrophysics there is less practical need for haste, but long delays can be frustrating.
|The BICEP2 telescope in the foreground and the South Pole Telescope in the background. Credit: Steffen Richter (Harvard University).|
What are some of the disadvantages of doing publicity before a paper is accepted to a journal?:
− The most important disadvantage: there is a chance a very good referee or referees will be found and the paper will be improved. It is possible that just the clarity of description or the references will be improved, but it is also possible that significant problems in analysis or interpretation will be found. For example, maybe the referee will be the world’s leading expert about crucial but problematic details of the analysis. This is a conservative approach to publicity, adopting the attitude that some independent checking is better than none.
In the case of BICEP2, their use of Planck data from a conference talk was problematic and they may not have properly accounted for all of the foreground emission, as explained in this paper submitted in late May by Raphael Flauger, Colin Hill and David Spergel. The Flauger et al. paper’s abstract finishes by saying:“These results suggest that BICEP1 and BICEP2 data alone cannot distinguish between foregrounds and a primordial gravitational wave signal, and that future Keck Array observations at 100 GHz and Planck observations at higher frequencies will be crucial to determine whether the signal is of primordial origin.“
In the published version of their paper, the BICEP2 authors, to their credit, have added a number of important caveats including this sentence added to the abstract: “However, these models are not sufficiently constrained by external public data to exclude the possibility of dust emission bright enough to explain the entire excess signal”. They also added this statement near the end of the paper: “More data are clearly required to resolve the situation.” If they had received some of this feedback about foreground emission from a referee or colleague before publicity, their press conference claims may have been made with less confidence.
− For academics, whether they like it or not, publishing papers in journals is still (*) one of the main arbiters of academic success. A successful paper isn't achieved until publication is complete and publication isn't complete until peer review is finished. So, by publicizing before peer review is finished you can give the appearance of adopting one standard for your scientific colleagues and a different, lower one for everyone else.
− With publicity, especially a press conference, you can reach a bigger or a much bigger audience than you would normally reach without publicity. The audience is the tax-paying public, who fund a large amount of research. So, as a matter of responsibility, standards of review should not be significantly lowered even if there are time pressures, such as fears of leaks or concern about being scooped by competitors.
My opinion is that the cons outweigh the pros in doing early publicity and that it is better for publicity to occur after peer review (this is approach #2 in the article by Heino Falcke). This approach shows that some effort has been taken by the authors to seek independent review of their work before publicity. It does not guarantee that the paper is flawless, but it does offer the chance to detect problems that were overlooked or not fully appreciated by the authors. For BICEP2, the changes made to the published version of their paper show that important improvements have indeed been made.
Others have questioned the timing of the BICEP2 publicity, including Bill Jones, a Princeton professor. Joel Achenbach’s excellent May 16th article in the Washington Post reports:
"Jones questioned the decision by the BICEP2 team to announce the discovery in a news conference prior to publication of a peer-reviewed paper. Kovac and Bock defended the news conference as a common procedure."
That may be true for physics press conferences, like ones held at the LHC, but not for NASA ones, where an accepted paper is required.
Traditional peer review isn’t magical and it is easy to imagine very rigorous, informal reviews that completely bypass the journal’s process. However, it’s not clear that the BICEP2 team encouraged such independent reviews before publicity, as in the submitted, publicized version of their paper they didn’t acknowledge receiving comments from colleagues.
The BICEP2 publicity was obviously very effective at generating press coverage. If the paper had been put on the arXiv before publicity, to generate widespread comments from colleagues, then some enterprising reporters may have picked up the article and written about it before a press release was produced. It’s possible that early submission to the arXiv was considered, but there was concern that early leaking of results to the press would have a negative effect on press coverage from a later release. How could the team combat this problem but also generate reasonably widespread reviews from colleagues? One option: they could have waited for peer review to be completed before doing publicity and also sent the paper to selected colleagues by email when it was submitted, with a strong request to keep the paper private.
If publicity is performed before publication, I think it’s best to put out a conservatively-worded press release, allowing for the possibility of errors, especially if the result is significant (this is approach #3 listed by Heino Falcke). However, the announcement by the BICEP2 team was confidently worded and did not mention the need for more data, unlike the wording used in the published version of their paper.
I have no doubt that the members of the BICEP2 team are excellent researchers at the top of their game, but the claim they made is extraordinary, and we all know the saying by Carl Sagan about what level of evidence is required for such a claim. It takes time and a lot of cross-checking to accumulate extraordinary evidence, and that’s what we should try to present to the public. There now appears to be a mismatch between the ebullient publicity of March 17th and the tempered claims in the paper published on June 19th. It’s important to think about whether this mismatch could reasonably have been avoided.
(*) Please see this blog post at Scientific American by Bonnie Swoger discussing whether the scientific journal has a future.