1. A method of adjusting process variables in a processing flow that comprises a sequence of processing steps, the method comprising: testing processed samples to determine sample parameters of the tested samples; analyzing said sample parameters in relation to the process variables applied in the processing steps to determine the impact of the process variables on the sample parameters; modifying the process variables in an attempt to change the sample parameters towards predetermined target values; and repeating the sequence of processing steps with the modified process variables; wherein the analyzing step includes, for given samples: automated matching between patterns of process variables applied for said samples and patterns of corresponding sample data sets of parameters determined from said samples; quantifying the degree of match in terms of score values associated with patterns of process variables; and determining the significance of said score values in terms of significance values calculated based on the deviation of the parameters in the sample data sets from said predetermined target values.