This paper considers methods of processing sorption equilibrium data so that the errors of derived information, such as maximum sorption capacity, can be calculated. The models considered in this study are the Langmuir and BET isotherms. In both cases the data are rearranged and correlated, on a standard spreadsheet, with a linear and quadratic function, respectively. Several estimates of the constants in the functions can be obtained by omitting data points in a consistent manner. These estimates can be statistically analyzed to give the mean and standard deviations of the constants. In obtaining the correlations on a spreadsheet, the coefficient of correlation (R-2) is obtained. Analysis of a large series of data would indicate that the value of R-2 does not give any information as to the variance of the coefficients in the correlating polynomial. The statistical analysis is finally illustrated with some examples.