In this paper, we present a method for assessing input parameters in a statistical model used for the quality analysis of the natural gas. The analysis is done by measuring physical quantities of natural gas through the hierarchy analysis, compromise programming, correlation analysis and assessing the practical possibility of measuring selected input physical quantities by available means. The problems arising when selecting input parameters are also considered. The results are compared with the previously obtained results of the model input parameters correlation analysis in order to improve the developed system for natural gas quality analysis. The proposed method is applied to assess input parameters for certain samples of natural gas based mixtures. Based on the results of the multicriteria assessment, the speed of sound, thermal conductivity and concentration of carbon dioxide were selected as input parameters for the developed natural gas quality analysis system.