Objective: We aimed to document the use of transparent reporting of hypotheses and analyses in behavioral medicine journals in 2018 and 2008.
Design: We examined a randomly selected portion of articles published in 2018 and 2008 by behavioral medicine journals with the highest impact factor, excluding manuscripts that were reviews or purely descriptive.
Main outcome measures: We coded whether articles explicitly stated if the hypotheses/outcomes/analyses were primary or secondary; if study was registered/pre-registered; if "exploratory" or a related term was used to describe analyses/aims; and if power analyses were reported.
Results: We coded 162 manuscripts published in 2018 (87% observational and 12% experimental). Sixteen percent were explicit in describing hypotheses/outcomes/analyses as primary or secondary, 51% appeared to report secondary hypotheses/outcomes/analyses but did not use term "secondary," and 33% were unclear. Registration occurred in 14% of studies, but 91% did not report which analyses were registered. "Exploratory" or related term was used in 31% of studies. Power analyses were reported in 8% of studies. Compared to 2008 (n=120), studies published in 2018 were more likely to be registered and less likely to have explicitly stated if outcomes were primary or secondary.
Conclusions: Behavioral medicine stakeholders should consider strategies to increase clarity of reporting, and particularly details that will inform readers if analyses were pre-planned or post-hoc.
Keywords: open science; pre-registration; research methods; scientific publication.