In this scientific paper it is presented the statistical analysis of the experimental data obtained by the study of the influence of the cutting parameters exerted in end-milling process on the surface roughness. The surface roughness parameter is measured in the cutting feed direction and against it. The parameters of the cutting process, the number of levels and their values were established. Based on these parameters, the research was designed on a complete factorial experiment, randomized with seven blocks. The surface roughness values were measured using a roughness tester. The research method used involved the Romanovski test. The aim of this test was to identify the data affected by aberrant errors, to remove them from the samples and then to repeat the tests for the remaining data strings until all values met the conditions imposed by the test.