1978/09/28 by Jennie A. Freiman, Thomas C. Chalmers, Harry Smith +4 · 4 citations
Chemistry · Decision Sciences · Economics, Econometrics and Finance · Mathematics · Medicine · #Chemical Synthesis and Reactions #Chemistry #Clinical trial #Confidence interval #Health Systems, Economic Evaluations, Quality of Life #Internal medicine #Medicine #Meta-analysis and systematic reviews #Organic Chemistry Cycloaddition Reactions #Randomized controlled trial #Sample size determination #Statistical Methods in Clinical Trials #Statistics #Synthesis and Catalytic Reactions #Type I and type II errors
paper · doi:10.1056/nejm197809282991304
openalex publication_date 1995/11/25 · openalex created_date 2016/06/24 · openalex updated_date 2026/06/11
Seventy-one "negative" randomized control trials were re-examined to determine if the investigators had studied large enough samples to give a high probability (greater than 0.90) of detecting a 25 per cent and 50 per cent therapeutic improvement in the response. Sixty-seven of the trials had a greater than 10 per cent risk of missing a true 25 per cent therapeutic improvement, and with the same risk, 50 of the trials could have missed a 50 per cent improvement. Estimates of 90 per cent confidence intervals for the true improvement in each trial showed that in 57 of these "negative" trials, a potential 25 per cent improvement was possible, and 34 of the trials showed a potential 50 per cent improvement. Many of the therapies labeled as "no different from control" in trials using inadequate samples have not received a fair test. Concern for the probability of missing an important therapeutic improvement because of small sample sizes deserves more attention in the planning of clinical trials.