The Linear Model Versus The Logistic Model in Regression on Qualitative Data. Regression on qualitative data is usually done by using a logistic model. By examining data where "everything is otherwise equal", one can show that the linear model is quite compatible with this type of data. Results of an in-deep analysis of cross-tabulation data (called tabular analysis ), and of regression using linear and logistic models, are quite similar (in terms of percentage effects). The theoretical question conceming the possibility of a linear model remains to be examined: it seems that the specific situation of a reference category introduces constraints which make the linear model possible.