The authors investigate the effects of errors on the slope of the Duehring lines on the calculated enthalpies, circulation ratios, and coefficients of performance (COPs) of absorption cycles. The technique used is based on random sampling of all possible values of the slope, with the number of samples proportional to the probability of the value given by a Gaussian distribution. The enthalpies, circulation ratios, and COP values corresponding to each value of the slope are calculated, generating COP distributions. These distributions are used to determine the sensitivity of COP calculations to errors on the slopes of the Duehring lines. In order to illustrate the method, it is applied to a well-characterized solution, lithium bromide and water. Two cycles, single-effect and double-effect, are analyzed. Application of the method to the single-effect cycle shows the standard deviation of the error in the slope. Furthermore, in all the cases analyzed, the standard deviations do not exceed 3. 0% of the zero errors COP. In addition, it was shown that high confidence can be placed in COP calculations, even if the standard deviation of the slope error is as high as 7. 5%, a large number by current experimental standards.