The element sensitivity factors method and the factor analysis are the most important methods for quantification of Auger depth profiles. The present paper puts forward a criterion for the decision in which cases the use of factor analysis is necessary for the quantification. The presented criterion uses the fact, that changed chemical bonds via sample depth are connected with changed element sensitivity factors. A chosen SiC-Si sample was investigated by Target Factor Analysis. The influence of data pretreatment like data selection, normalization and filtering are discussed.