Wheeler, Frederick P., "Focusing on the Growth Rate of Technological Adoption", 1986
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Models of substitution and adoption of consumer durable technologies typically focus on the level of adoption or the level of cumulative sales of the product. Although these variables may be of interest, decisions on market entry and the judgement of future return on investment are linked to the rate of change in adoption level. The percentage change in the current level of adoption, the growth rate, is more relevant, more meaningful and more sensitive a measure of past and future trends than is the level itself. This is an appeal for system modellers and forecasters to focus their attention on growth in studies of technological diffusion.