Key points are not available for this paper at this time.
Pradeep K. Chintagunta, Dipak C. Jain, Naufel J. Vilcassim, Investigating Heterogeneity in Brand Preferences in Logit Models for Panel Data, Journal of Marketing Research, Vol. 28, No. 4 (Nov., 1991), pp. 417-428
Chintagunta et al. (Fri,) studied this question.