Methods for selecting descriptors for constructing linear quantitative structure-retention relationships are not reproducible with respect to changes in the data set. Different selection methods give different results. Conclusions about the retention mechanism and comparison of stationary phases based on such quantitative relationships must be made with extreme caution. Some previous works did not carry out any checks on the reproducibility of the selection of descriptors, but qualitative conclusions were drawn from the fact which descriptors were selected. Such conclusions are unreliable and should be avoided.