Baseline-dependent improvement in CF studies, plausibility of bias.

Background: It has been commonly reported that therapeutic treatments in cystic fibrosis (CF) have ceiling effects, such that their efficacy is diminished for persons with high pre-treatment health (Montgomery et al., 2012 and Newsome et al., 2019).

Impact of day-to-day variation in FEV1 on measures of change: A conceptual description.

Clinical trials often demonstrate treatment efficacy through change in forced expiratory volume in one second (FEV), comparing single FEV measurements from post- versus pre-treatment timepoints. Day-to-day variation in measured FEV is common for reasons such as diurnal variation and intermittent health changes, relative to a stable, monthly average. This variation can alter estimation of associations between change in FEV and baseline in predictable ways, through a phenomenon called regression to the mean.

Contribution of Glottic Insufficiency to Perceived Breathiness in Classically Trained Singers.

Breathiness in the singing voice is problematic for classical singers. Voice students and singing teachers typically attribute breathiness to breath management issues and breathing technique. The present study sought to determine whether glottic insufficiency may also contribute to breathiness in a singer's voice.