2.3 Technology Forecasting Methods
Forecasting methods can be classified as either extrapolative or normative—that is, by whether they extend present trends or look backward from a desired future to determine the developments needed to achieve it. Although this is a useful distinction, many methods can be considered either normative or extrapolative, depending on how they are applied. Further, the classifications can be confused with the perspective of the planning or decision-making activity that the forecast is intended to inform.
Porter and Rossini (1987) suggest that the hundreds of forecasting techniques fit into five families:
2. Expert opinion
3. Trend extrapolation
This system has some limitations. Monitoring is not a forecasting method per se but rather a systematic method used to accumulate and analyze data from which forecasts are made. Further, it is unclear where to place forecasts made by analogy or those that employ lead-lag indicators. It can be helpful to categorize methods by whether they are direct, correlative, or structural. Table 2.4 indicates how some of the more common techniques might be categorized in the latter framework.
Direct methods forecast parameters that measure functional capacity or some other relevant characteristic of the technology. These methods do not explicitly consider correlations with technological, economic, social, and political contexts, nor do they consider structural relationships within ...