The Dirichlet (aka NBD-Dirichlet) model describes the probability distributions of the consumer purchase incidences and brand choices. We estimate the model and calculate various theoretical quantities of interest to marketing researchers.
The Dirichlet: A Comprehensive Model of Buying Behavior. G.J. Goodhardt, A.S.C. Ehrenberg, C. Chatfield. Journal of the Royal Statistical Society. Series A (General), Vol. 147, No. 5 (1984), pp. 621-655
Repeat-Buying:Facts,Theory and Applications, 2nd edn. A.S.C. Ehrenberg, 1988, London, Charles Griffin, ISBN 0 85264 287 3
Book Review: Repeat-Buying:Facts,Theory and Applications by A.S.C. Ehrenberg. Norman Pigden. The Statistician, Vol. 40, No. 3, Special Issue (1991), pp. 349-350
cat.pen <- 0.56 # Category Penetration cat.buyrate <- 2.6 # Category Buyer's Average Purchase Rate in a given period. brand.share <- c(0.25, 0.19, 0.1, 0.1, 0.09, 0.08, 0.03, 0.02) # Brands' Market Share brand.pen.obs <- c(0.2,0.17,0.09,0.08,0.08,0.07,0.03,0.02) # Brand Penetration brand.name <- c("Colgate DC", "Macleans","Close Up","Signal","ultrabrite", "Gibbs SR","Boots Priv. Label","Sainsbury Priv. Lab.") dobj <- dirichlet(cat.pen, cat.buyrate, brand.share, brand.pen.obs, brand.name) print(dobj) summary(dobj) # plot(dobj)
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