background: noise-induced hearing loss (nihl) is one of the most common occupational diseases and the second most common cause of workers' claims for occupational injuries. objective: due to high prevalence of nihl and several reports of improper use of hearing protective devices (hpds), we conducted this study to compare the effect of face-to-face training in effective use of earplugs with app...

Many clinical trials of uncommon diseases are underpowered because of the difficulty of recruiting adequate numbers of subjects. We propose a clinical trial design with improved statistical power compared to the traditional randomized trial for use in clinical trials of rare diseases. The three-stage clinical trial design consists of an initial randomized placebo-controlled stage, a randomized ...