The reliability of magnitude estimation for dyspnea measurement.
 The reliability of magnitude estimation with an open scale was evaluated in a physiologically stable population of adults with chronic respiratory disease who experienced chronic dyspnea.
 Magnitude estimation was used to measure one dimension of dyspnea, perceptual sensitivity.
 The relationship between external inspiratory resistive loads (stimuli) and numbers that reflected the perceived intensity of the breathing effort (response) as expressed by a power function was measured on three visits 3 to 5 days apart.
 The correlations of the exponent of the power function between visits were high and stable.
