Authors to correct PNAS ‘nudge’ paper that cites now-retracted article in the same journal

The authors of a paper on “nudge experiments” published last week in the Proceedings of the National Academy of Sciences (PNAS) plan to correct it following questions about some of its conclusions and citations, Retraction Watch has learned.

Following up on comments by Aaron Charlton and Nick Brown, Columbia University’s Andrew Gelman, who is deeply skeptical of the findings, raised several questions about the paper in a post on January 7. Among them were that the paper cites 11 articles by food marketing researcher Brian Wansink, whom Retraction Watch readers may recall resigned from his post at Cornell following an investigation and has had 17 papers retracted, one of them twice.

Gelman also notes that the paper cites a paper by Dan Ariely and colleagues that was retracted in September. We’ll focus here on the inclusion of that reference.

Co-corresponding author Tobias Brosch, of the University of Geneva, responded within hours of Gelman’s post, writing in part:

As for the paper by Shu et al. (2012), we would like to point out that we did in fact exclude the highly criticized field experiment conducted by Dan Ariely from our analyses (this exclusion occurred during the revision stage of our paper when the paper by Shu et al. was being critically discussed, but had not yet been officially retracted). In the absence of any evidence pointing to similar scientific misconduct in the implementation and analysis of the lab experiments reported in the paper, we decided to include these lab experiments in our analyses as we considered them a valid part of the scientific literature.

We asked Brosch:

Do I understand correctly that the Ariely et al paper was excluded from your analysis, but that the paper doesn’t explicitly say that? Or does it fall under one of the described exclusion criteria?

Brosch responded:

By the time we submitted the revised version of our paper, the Shu et al., 2012 paper was being critically discussed in the social media, but had not yet been officially retracted. We decided to exclude the highly criticized field experiment conducted by Dan Ariely (Study 3 of the paper) from our analyses, but included the two lab experiments (Studies 1 and 2), as there was no evidence pointing to similar scientific misconduct in the implementation and analysis of the lab experiments (the restriction to Studies 1 and 2 is indicated in the supplementary information, Table S1).

The reference to the paper in Table S1 does read:

As noted by Charlton in a comment on Gelman’s post, five of the authors of the 2012 paper later said that the two experiments did not replicate.

We followed up:

So I take it the revision was submitted before September 14 [the paper was retracted on Sept. 13]? Was any consideration given to noting the retraction once the paper was accepted on November 24 and before it was published?

Brosch replied:

We did not eliminate the first two studies from the dataset before our meta-analysis was published, but I agree with you that also the first two studies should be excluded in order to reflect the state of the literature at the moment of the publication of the meta-analysis. We are currently working on a corrigendum where we will (i) exclude all experiments from the now retracted Shu et al paper, and (ii) update two data points from a paper by Rohlfs and colleagues which are likely incorrect because the authors provided us with wrong data in a personal communication (we recontacted them to confirm and correct if needed, and are still waiting for their feedback). 

Whatever the right answer for this paper is, we’ll note here that the immediate and non-defensive response, coupled with the move to begin work on a corrigendum, is the sort of thing we see all too-rarely.

And the case may prompt some changes at PNAS. Editor in chief May Berenbaum told Retraction Watch that “yes, I think references in supplementary information files should indeed be checked.” Managing editor Daniel Salisbury told us that “Currently, PNAS supporting information is published as provided by the authors; it is not edited or composed.”

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