PREDICTIONS – 10 Years Later - Santa Fe Institute

1. SCIENCE AND FORETELLING
NATURAL GROWTH
Rate of
growth
Cumulative
growth
Time
FIGURE 1.3 While the rate of growth follows a bell-shaped curve, the cumulative
growth traces out an S-curve.
The overall size obtained as a cumulative number, be it height, number
of concerts, or products sold, can never decrease, although in real
life a person’s height does, in fact, decrease somewhat with old age.
Just as an S-curve can be obtained from a life cycle by measuring the
cumulative rate of growth over time, one can calculate a life cycle from
the S-curve through successive subtractions. For example, monitoring a
plant’s growth over the days by plotting its height on graph paper produces
and overall S-curve. If one is interested in the life cycle of the
process, one must subtract from each day’s measurement the previous
day’s, thus producing a set of numbers representing growth per day,
which will follow the bell-shaped curve of the natural life cycle.
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