A group of researchers in the United States and China have retracted their 2018 paper on hand hygiene, admitting that they can’t account for “data anomalies” in their work.
The article in question, “The decoy effect as a nudge: Boosting hand hygiene with a worse option,” appeared in Psychological Science last May. Led by Meng Li, of the Department of Health and Behavioral Sciences at the University of Colorado Denver, the researchers reported results from experiments designed to increase the use of hand sanitizer in the workplace through the use of a “decoy” bottle:
This article provides the first test of the decoy effect as a nudge to influence real-world behavior. The decoy effect is the phenomenon that an additional but worse option can boost the appeal of an existing option. It has been widely demonstrated in hypothetical choices, but its usefulness in real-world settings has been subject to debate. In three longitudinal experiments in food-processing factories, we tested two decoy sanitation options that were worse than the existing sanitizer spray bottle. Results showed that the presence of a decoy, but not an additional copy of the original sanitizer bottle in a different color, drastically increased food workers’ hand sanitizer use from the original sanitizer bottle and, consequently, improved workers’ passing rate in hand sanitation tests from 60% to 70% to above 90% for 20 days. These findings indicate that the decoy effect can be a powerful nudge technique to influence real-world behavior.
Shortly after an in-press version of the article appeared online, however, Leif Nelson, of UC Berkeley’s Haas School of Business — and a founder of the Data Colada blog — read the study and became suspicious about the plausibility of the findings.
We won’t re-hoist all of the red flags here; for that, read the account on Data Colada. But the issues were compelling enough that the editor of the journal agreed action was needed.
In December, the journal issued a lengthy correction stating, in part, that:
The original online-first version of this article included some errors that are now being corrected. These changes do not affect the statistical results or the conclusions of the experiments.
The journal also published a detailed expression of concern. That notice, which thanks Nelson et al for their efforts, lays out the various flaws with the article, including “uncertainty regarding the provenance of the data” and “peculiarities” with the results.
However, the correction/expression of concern didn’t satisfy the Data Coladans, who wrote:
Even after the correction, and the clarifications of the Expression of Concern, we still believe that these data do not deserve the trust of Psychological Science readers.
Now, more than a year after publication of the original article, the journal is retracting the work.
According to the notice:
The following article has been retracted at the request of the first two authors (Meng Li and Yan Sun): Li, M., Sun, Y., & Chen, H. (2019). The decoy effect as a nudge: Boosting hand hygiene with a worse option. Psychological Science, 30, 139–149. doi:10.1177/0956797618761374
Li and Sun notified the Editor as follows:
In December 2018, we requested that an Expression of Concern be issued for our article because of anomalies in the data (brought to our attention by Leif Nelson, Frank Yu, Uri Simonson, and two anonymous researchers) and because we were not able to recover records of the messages containing the original data files that the factories sent to the third author (Chen), who was the sole point of contact with the factories where the data were collected. Since then, we have made many attempts to obtain more information about the data collection process. Unfortunately, Chen has not provided additional information, and we have not found a convincing alternative explanation for the data anomalies. While there is no direct proof that the data were tampered with, our faith in the data is substantially reduced, and we judge that it is necessary to retract the article.
Simonsohn told us that he is “quite satisfied with the paper getting retracted.”
Like Retraction Watch? You can make a tax-deductible contribution to support our work, follow us on Twitter, like us on Facebook, add us to your RSS reader, sign up for an email every time there’s a new post (look for the “follow” button at the lower right part of your screen), or subscribe to our daily digest. If you find a retraction that’s not in our database, you can let us know here. For comments or feedback, email us at email@example.com.