Diffusion of Innovations

Paul Marsden (PaulMarsden@email.msn.com)
Thu, 10 Sep 1998 07:50:22 +0100

From: "Paul Marsden" <PaulMarsden@email.msn.com>
To: "memetics" <memetics@mmu.ac.uk>
Subject: Diffusion of Innovations
Date: Thu, 10 Sep 1998 07:50:22 +0100

Mes chères Derek and Aaron

It's great to see people referring, albeit obliquely, to research on
contagion and diffusion. Chapter 2, entitled "Contagion and Diffusion" in
Rapoport's Mathematical Models in the Social and Behavioural Sciences (1983)
might be illuminating for memeticists who want to know how contagion and
diffusion processes are linked.

Rogers himself (1983) defines innovation as

"Innovation: An innovation is an idea, practice, or object that is perceived
as new by an individual or other unit of adoption."

So yes, an innovation may include mental memetics. But, and this is
critical, the only way of measuring them is through resultant behaviour.
Diffusion/contagion research is the principal alternative in the social
sciences to Rational Choice Theory (operationalised through conjoint
analysis) for predicting Customer Behaviour.

The basic principle of diffusion research is to model and predict the
market penetration of new products, that is purchasing behaviour. Now in
order to do this we have to posit a number of values that when added to the
formula, model the relationship between (awareness) exposure and infection
(purchase - customer behaviour). In the case of diffusion these the
coefficients of imitation and the coefficient of innovation. (I have just
been involved with building such a model for Pfizer and Viagra in the UK)

The basic equation upon which diffusion works is the Bass Equation which
states that

f(k + 1) = p[1 - F(k)] + qF(k)[1 - F(k)]

f(k) = probability of adoption in period k
F(k) = fraction of ultimate potential that has adopted through period k
p = coefficient of innovation
q = coefficient of imitation

An extra weight is also usually added to the communication channel - i.e.
depth and breadth of exposure

The coefficient of innovation is comprised of five attributes of the

Relative Advantage:
"the degree to which an innovation is perceived as being better than the
idea it supersedes."
"the degree to which an innovation is perceived as being consistent with
existing values, past experiences, and needs of potential adopters."
"the degree to which an innovation is perceived as difficult to understand
and use."
"the degree to which an innovation may be experimented with on a limited
"the degree to which the results of an innovation are visible to others."

These factors can be, and are, quantified through market research
(researchers have developed techniques that indirectly assess these
factors.) Now, in 1971 Rogers an Shoemaker reviewed over 700 empirical
studies of BEHAVIOUR that evaluated the weight of the different variables
that impacted on contagion. It might just be worthwhile building on this
research in building memetic models.

Rogers, E.M. & Shoemaker, F.F. (1971) Communication of Innovations. (2nd
Ed.) NY. The Free Press
Now in 1970
Rapoport, A (1983) Mathematical Models in the Social and Behavioural

Paul Marsden
Graduate Research Centre in the Social Sciences
University of Sussex
e-mail PaulMarsden@msn.com
tel/fax (44) (0) 117 974 1279

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