Transfer Curves

Transfer curves describe the replacement of one technology with another.  Two examples:

In 1945, all commercial air travel was in aircraft with reciprocating piston engines driving propellers, example being the Douglas DC4 and DC6.  By 1960, jet powered airliners such as de Havilland Comet and the Boeing 707 were asserting themselves at the expense of aircraft such as the Lockheed Constellaton.  By 1980, the transition was almost complete.

Early consumer electronic devices were based on vacuum tubes (e.g. triodes, pentodes and CRTs)  A TV set from the 1950s was as much a source of warmth as entertainment.  By 1990, semiconductors had replace thermomic valves and by 2000, solid state displays had replaced CRTs.

The substitution can be partial.  Whilst not often referred to as technology, this can be illustrated by by women's clothing.  At the start of the 20th century, there are few fashion plates of women concealing their legs with anything other than a skirt, by the start of the 21st century, many women have trousers and skirts in their wardrobe.

The graph below shows a hypothetical transfer curve in which Technology A partially substitutes Technology B over an indeterminate time period.

Transfer curves are a form of time series.  Whilst they are quite easy to do with hindsight, forecasting the trajectory of a substitution process in the early stages is difficult and often relies on subjective assessments (or vision as it is sometimes called in business schools).  The above example was compiled by setting the stand and end points and filling in the intervening period with values from a logistic function.

An example of a partial substitution process which is in its early stages is the growing use of mobile devices to to access the internet.  The experience of this site to date, is shown in the graph below:

The increasing use of smart phones will affect different parts of the internet defferently, therefore general forecasts should be treated with care.  Also, the process of substitution is superimposed on trends in overall demand and any associated seasonality.