Abstract
Four competing models were developed to test assumptions about the workings of the respiratory controller. These models were tested against previously published data and unknown parameters estimated with a leastsquares procedure. It was found that similar fits were obtained on data from men not at exhaustion by minimizing total respiratory power or inspiratory power only. Inspiratory power alone gave good fit at exhaustion. Also, mask resistance was found to be unequivalent to respiratory resistance in determination of respiratory period.