PREDICTIONS – 10 Years Later - Santa Fe Institute

6. A HARD FACT OF LIFE
DETERGENTS SUBSTITUTING FOR SOAP for Soap
FIGURE 6.3 The data points represent the ratio of detergents to soap consumed
annually in the United States and Japan. The vertical scale is logarithmic, which
makes the fitted S-curves (intermittent lines) appear straight. The numbers at
the scale gradations do not refer to values of the ratio, however, but to market
shares instead. We can say that a graph constructed in this way makes use of a
logistic scale. We see the rise of detergents; the complementary decline of soap
is not shown. ∗
∗ Adapted from a graph by J. C. Fisher and R. H. Pry in “A Simple Substitution Model of
Technological Change,” Technological Forecasting and Social Change, vol. 3, no. 1
(1971): 75–88. Copyright 1971 by Elsevier Science Publishing Co., Inc. Reprinted by
permission of the publisher.
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