{"doi":"10.31234/osf.io/b3uwd","title":"Recommendations in pre-registrations and internal review board proposals promote formal power analyses but do not increase sample size","abstract":"<p>In this preregistered study, we investigated whether the statistical power of a study is higher when researchers are asked to make a formal power analysis before collecting data. We compared the sample size descriptions from two sources: (i) a sample of pre-registrations created according to the guidelines for the Center for Open Science Preregistration Challenge (PCRs) and a sample of institutional review board (IRB) proposals from Tilburg School of Behavior and Social Sciences, which both include a recommendation to do a formal power analysis, and (ii) a sample of pre-registrations created according to the guidelines for Open Science Framework Standard Pre-Data Collection Registrations (SPRs) in which no guidance on sample size planning is given. We found that PCRs and IRBs (72%) more often included sample size decisions based on power analyses than the SPRs (45%). However, this did not result in larger planned sample sizes. The determined sample size of the PCRs and IRB proposals (Md = 90.50) was not higher than the determined sample size of the SPRs (Md = 126.00; W = 3389.5, p = 0.936). Typically, power analyses in the registrations were conducted with G*power, assuming a medium effect size, α = .05 and a power of .80. Only 20% of the power analyses contained enough information to fully reproduce the results and only 62% of these power analyses pertained to the main hypothesis test in the pre-registration. Therefore, we see ample room for improvements in the quality of the registrations and we offer several recommendations to do so.</p>","journal":"PsyArXiv (OSF Preprints)","year":null,"id":39218,"datarank":0.24470023476125063,"base_score":1.3862943611198906,"endowment":1.3862943611198906,"self_citation_contribution":0.20794415416798362,"citation_network_contribution":0.03675608059326702,"self_endowment_contribution":0.20794415416798362,"citer_contribution":0.03675608059326702,"corpus_percentile":39.82362497099095,"corpus_rank":7779,"citation_count":3,"citer_count":1,"citers_with_citation_signal":1,"citers_with_endowment":1,"datacite_reuse_total":0,"is_dataset":true,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":59.1667,"fair_percentile":69.31567328918322,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":193080,"name":"Coosje Lisabet Sterre Veldkamp","orcid":null,"position":1,"is_corresponding":false},{"id":4914,"name":"Olmo R. van den Akker","orcid":"0000-0002-0712-3746","position":2,"is_corresponding":false},{"id":20278,"name":"Marcel A. 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