Journal of Applied Physiology, Vol 56, Issue 2 536-539, Copyright © 1984 by American Physiological Society
Estimation of response slopes in respiratory control
D. L. Sherrill and G. D. Swanson
The ventilatory response to changes in alveolar (arterial) CO2 is widely
used as an index of respiratory control behavior. Methods for estimating
these response slopes should incorporate the possibility that there may be
errors in both the independent (partial pressure of CO2) and dependent
(ventilation) variables. In a recent paper Daubenspeck and Ogden (J. Appl.
Physiol. Respirat. Environ. Exercise Physiol. 45:823-829, 1978) have
suggested problems inherent in the traditional technique of reduced major
axis and have suggested a more contemporary technique of directional
statistics. We have previously analyzed both techniques and developed a
method to overcome the problems of reduced major axis and problems inherent
in the use of directional statistics. Under the assumption of a bivariate
normal distribution, we demonstrate that our slope estimate is similar to
the maximum likelihood estimate proposed by Mardia et al. (J. Appl.
Physiol.: Respirat. Environ. Exercise Physiol. 54: 309-313, 1983) for this
problem. In addition, we demonstrate a bootstrap statistical approach when
the distributions are not normally distributed. These concepts are
illustrated using O2-CO2 interaction data.
