163 diseconomies of scale
(1) each buyer or buying unit has a steady as-if-random buying probability
(i.e. these probabilities are Poisson distributed across the market);
(2) there is a smooth (gamma) distribution of light, medium, and heavy
buyers; (3) each buyer uses a portfolio of brands with steady probabilities
and these probabilities are represented by a multinomial distribution
across those in the market; (4) individuals’ buying probabilities follow
a smooth beta distribution across the market; and (5) brand choice is
independent of purchase incidence. These assumptions enable analysis
and prediction of a wide range of brand performance measures such
as penetration, purchase frequency, and loyalty. There are a number of
generalizations stemming from research involving the Dirichlet model-
ing approach, and one of the most notable is an effect termed ‘double
jeopardy.’ (See double jeopardy effect.)
KEY WORDS Loyalty, brand choice
IMPLICATIONS
Marketers concerned with the study of loyalty and brand choice through
the development and use of sophisticated marketing models may benefit
from a greater understanding of the Dirichlet modeling approach as
it can assist the marketer with identifying many buying patterns with
minimal inputs. As its applicability has been demonstrated across a range
of product markets, marketers wishing to adopt a modeling approach
that is not only simple and easy to operationalize but relatively robust
may find the Dirichlet modeling approach to be particularly beneficial.
APPLICATION AREAS AND FURTHER READINGS
Marketing Strategy
Stern, P., and Hammond, Kathy (2004). ‘The Relationship between Customer Loy-
alty and Purchase Incidence,’ Marketing Letters, 15(1), 5–19.
Marketing Modeling
Fader, Peter S., and Schmittlein, David C. (1993). ‘Excess Behavioral Loyalty for
High-Share Brands: Deviations from the Dirichlet Model for Repeat Purchasing,’
Journal of Marketing Research, 30(4), November, 478–493.
Uncles, Mark, Ehrenberg, A. S. C., and Hammond, Kathy (1995). ‘Patterns of Buyer
Behavior: Regularities, Models, and Extensions,’ Marketing Science, 14(3), G71–G78.
Marketing Research
Ehrenberg, A. S. C., Uncles, M. D., and Goodhardt, G. J. (2004). ‘Understanding
Brand Performance Measures: Using Dirichlet Benchmarks,’ Journal of Business
Research, 57(12), 1307–1325.
BIBLIOGRAPHY
Goodhardt, G. J., Ehrenberg, A. S. C., and Chatfield, C. (1984). ‘The Dirichlet: A
Comprehensive Model of Buying Behaviour,’ Journal of the Royal Statistical Society,
Series A (General), 147(5), 621–655.
discriminant validity see validity
diseconomies of scale
DESCRIPTION
Increasesin unit product costs resulting from an increase in production output.