Psychological science recently has drawn widespread public attention as a result of a new report estimating the reproducibility of studies in the field. This report, published in Science, showed that fewer than half of the psychology studies from a sample of 100 replicated. These results are eye-opening for many researchers from many fields, but they present a unique opportunity for psychological scientists to advance reproducibility and openness in science generally.
“I feel like we are really stepping to the plate and leading the way,” APS Fellow Jonathan Schooler (University of California, Santa Barbara) told The New York Times.
The report, coordinated by APS Fellow Brian Nosek (University of Virginia) and the Center for Open Science in Charlottesville, Virginia, involved recruiting more than 270 researchers who attempted to reproduce 100 findings published in psychology journals in 2008.
Among the 100 studies selected for the replication project were 40 published in APS’s flagship journal, Psychological Science. Replication teams worked with the authors of the original studies when possible and posted their data and analyses online for public evaluation. The set of replications took more than 3 years to complete.
The replication teams’ findings were striking: Overall, 97% of the original studies reported statistically significant p values below .05, but only 36% of the replication studies found statistically significant results (p < .05). Moreover, whereas the effect sizes in the original studies were moderate, on average — Pearson r = .40 — in the replications, the sizes of the effects were r = .20 — half as large as the originals.
Nosek and colleagues also assessed differences within subfields of psychology. Cognitive psychology studies were twice as likely to replicate as were social psychology studies, but both subfields showed equivalent decreases in effect sizes in the replication attempts. The researchers also searched for factors associated with whether a replication attempt succeeded or failed. Success was related to the original strength of evidence, but not to factors such as the experience or expertise of the replication team.
Just because a study was not replicated does not mean it was wrong, however. Replication failures sometimes can occur when the replication misses detecting a real effect or when the methodology of the replication differs in important ways from the methodology of the original study.
According to Nosek, studies also may fail to reproduce because scientists are rewarded for getting research published, and some findings simply are more likely to be accepted
“I am more likely to get published for a positive result than a negative, with a novel result than a registered replication, and with a very clean story, as opposed to one with lots of loose ends,” he stated at a recent presentation at the National Science Foundation. “Because we’re incentivized to make it a novel, positive, clean story, then, there’s lots of reasons for me and for my individual success to find ways to make it as beautiful as possible, even if that makes it look a lot different from what the actual evidence is.”
The project findings probably mean that psychological science needs to devote more attention to improving reproducibility, Nosek emphasized in a teleconference announcing the results of the report.
“But I don’t see this story as pessimistic,” he added. “The project is a demonstration of science demonstrating one of its central qualities — self-correction.”
Indeed, APS has been encouraging self-correction in psychological science, APS Executive Director Emeritus Alan G. Kraut commented in the same teleconference.
“We have changed how articles are published in Psychological Science, changes that encourage greater transparency and stronger statistical analyses and that provide special recognition for preregistering hypotheses and for sharing materials and data,” he said. “APS also is pushing at the leading edge on issues of replicability.”
The badge program recognizing open science practices, Registered Replication Reports, and the Transparency and Openness Promotion Guidelines, to which APS is a signatory, are three examples of APS’s efforts in this arena. These programs are likely to lead to an improvement in the reproducibility of psychological science, said Interim Editor of Psychological Science D. Stephen Lindsay in a statement.
“It is exciting to anticipate a future replication of this extraordinary project in, say, 8 years, testing the replicability of articles published in Psychological Science in 2016. If we do our jobs correctly then the replication rate will be dramatically higher,” he said.
“Replication is a fundamental part of science — it is science at its best,” Kraut echoed.