Registered trials report less beneficial treatment effects than unregistered ones: a meta-epidemiological study in orthodontics.OBJECTIVES

Meta-epidemiological study
After duplicate study selection and data extraction, statistical analysis included a two-step meta-epidemiological approach within- and across-included meta-analyses with a Paule-Mandel random-effects model to calculate differences in standardized mean differences (ΔSMD) between registered and unregistered trials and their 95% confidence intervals (CI), followed by subgroup and sensitivity analyses.



Paule-Mandel random-effects model