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Pharyngeal Pressures During Swallowing Within and Across Three Sessions: Within-Subject Variance and Order Effects

No studies have investigated within-subject variation in measures of pharyngeal pressures during swallowing across sessions. This study aimed to document the variation in pharyngeal pressures both within and across three sessions. Twenty healthy participants were recruited for three sessions. For each session, peak or nadir pressures were recorded from the upper pharynx (sensor 1), mid-pharynx (sensor 2), and upper esophageal sphincter (sensor 3) during saliva and 10-ml water bolus swallows. Variance was larger across sessions than within sessions for sensors 1 and 2 but comparable for sensor 3. For all sensors there was a high correlation between the variance across sessions and within session (r = 0.92, p < 0.0001). There were no significant order effects of session or of trial at any sensor with estimated order effects less than 2% and the estimated maximum possible change no larger than 5% for trial and no larger than 12% for session. These data offer direction for longitudinal treatment studies in which pharyngeal pressures are an outcome measurement by (1) providing a basis for power calculations, (2) estimating the likely values of any confounding order effects, and (3) providing suggestions for more reliable data analysis.

from Dysphagia

Gender ratios for reading difficulties

Abstract
The prevalence of reading difficulties is typically higher in males than females in both referred and research-identified samples, and the ratio of males to females is greater in more affected samples. To explore possible gender differences in reading performance, we analysed data from 1133 twin pairs in which at least one member of each pair had a school history of reading problems and from 684 twin pairs from a comparison sample with no reading difficulties. Although the difference between the average scores of males and females in these two samples was very small, the variance of reading performance was significantly greater for males in both groups. We suggest that a greater variance of reading performance measures in males may account at least in part for their higher prevalence of reading difficulties as well as for the higher gender ratios that are observed in more severely impaired samples. Copyright © 2009 John Wiley & Sons, Ltd.

from Dyslexia