taken from: Hannes Datta, Kusum L. Ailawadi , and Harald J. van Heerde (2017) How Well Does Consumer Based Brand Equity Align with Sales Based Brand Equity and Marketing Mi x Response?. Journal of Marketing: May 2017, Vol. 81, No. 3, pp. 1 20.
taken from: Datta, H., Foubert, B., & Van Heerde, H. J. (2015). The challenge of retaining customers acquired with free trials. Journal of Marketing Research, 52(2), 217 234.