Abstract
This article discusses the impact of choosing a data preprocessing method for the calculated gas density necessary to determine the sorption capacity of a material. The sample of gas-bearing shale was subjected to a volumetric sorption test. The obtained data, pressure and temperature were preprocessed by three methods: moving average, polynomial regression and locally weighted scatterplot smoothing. The results include the excess and absolute sorption calculated from data that were filtered, and data without pre-treatment and Langmuir isotherms’ coefficients for every case.