Sample size, sample size planning, and the impact of study context: systematic review and recommendations by the example of psychological depression treatment.

ABSTRACT:

Background

Sample size planning (SSP) is vital for efficient studies that yield reliable outcomes. Hence, guidelines, emphasize the importance of SSP. The present study investigates the practice of SSP in current trials for depression.

Methods

Seventy-eight randomized controlled trials published between 2013 and 2017 were examined. Impact of study design (e.g. number of randomized conditions) and study context (e.g. funding) on sample size was analyzed using multiple regression.

Results

Overall, sample size during pre-registration, during SSP, and in published articles was highly correlated (r's ≥ 0.887). Simultaneously, only 7-18% of explained variance related to study design (p = 0.055-0.155). This proportion increased to 30-42% by adding study context (p = 0.002-0.

SUBMITTER: Schuster R 

PROVIDER: S-EPMC8161431 | biostudies-literature | 2021 Apr

REPOSITORIES: biostudies-literature