Relation
Between Purchase Intention & Actual Adoption
A
proven model for adjusting stated purchase intention is utilized to
improve the predictive accuracy of initial purchases of new
technologies (Jamieson, Linda F. & Bass, Frank M., "Adjusting
Stated Intention Measures to Predict Trial Purchase of New Products:
A Comparison of Models & Methods," Journal of Marketing
Research, August 1989). This model is based on the largest and
most comprehensive database on purchase intention & actual
purchase behavior for new products, such as home computers &
cordless phones.
This
model takes into account that many factors will affect trial of new
products, such as awareness, liking, availability & affordability.
By providing a valid framework for including these variables rather
than relying only on stated purchase intentions (e.g., the percentage
of consumers who say they will "definitely" or
"probably" acquire DSR), more accurate predictions of
initial purchases are made.
Rate
of Diffusion
The
Bass model of diffusion is used to estimate the speed new
technologies will be adopted (Bass, Frank M., "A
New Product Growth Model for Consumer Durables," Management
Science, January 1969). The Bass model of diffusion has been
widely used to successfully predict the growth rate of numerous new
& innovative technologies, including color TV, VCRs, telephone
answering machines, overhead projectors, mainframe computers, direct
broadcast satellite television, and recording media (records, tapes &
CDs).
The
Bass model for forecasting first purchase has had a long history in
marketing. It is most
appropriate for forecasting sales of an innovation (more generally a
new product) for which no closely competing alternatives exist in the
marketplace. The Bass
model offers a good starting point for forecasting the long-term sales
pattern of new technologies and new durable products under two types
of conditions:
-
The
firm has recently introduced the product or technology and has
observed its sales for a few time periods, or
-
The
firm has not yet introduced the product or technology, but is
similar
in some way to existing products or technologies whose
sales history is known.
The
basic assumption of the model is that the probability of a consumer's
initial purchase is related linearly to the number of previous buyers.
Buyers are composed of both innovators & imitators. The
number of previous buyers does not influence innovators in the timing
of their initial purchase, while imitators are strongly affected by
the number of adopters. Innovators therefore have greater
importance in the early stages of new product adoptions than after the
product becomes more widely disseminated.
This
model implies exponential growth of initial purchases to a peak and
then exponential decay. The slope of the diffusion curve is
therefore a function of the rate that awareness of the new product is
developed, as well as the product's appeal.
The
model attempts to predict how many customers will eventually adopt the
new product and when they will adopt.
Bass suggests that the likelihood (L(t))
that a customer will adopt an innovation at time t
(given that the customer had not adopted before) could be
characterized as:
where...
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