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and boasting of a ―glorious past(i.e. adopting the same old techniques).‖‖3.2 Technological Forecasting MethodsThe major techniques for technological forecasting may be categorized under two general headings:methods based on numeric data and judgmental methods. In the main, numeric data-based forecastingextrapolates history by generating statistical fits to historical data. A few numeric methods deal withcomplex interdependencies. Judgmental forecasting may also be based on projections of the past, butinformation sources in such models rely on the subjective judgments of experts. Again, we emphasize thattechnological forecasting is most appropriately applied to capabilities, not to the specific characteristics ofspecific devices.Numeric Data-Based Technological Forecasting Techniques:Trend ExtrapolationTo extrapolate is to infer the future from the past. If there has been a steady stream of technologicalchange and improvement, it is reasonable to assume that the stream will continue to now. We candistinguish four approaches to the use of trend extrapolation.Statistical Curve FittingThis method is applicable to forecasting functional capabilities. Statistical procedures fit the past data toone or more mathematical functions such as linear, logarithmic, Fourier, or exponential. The best ht isselected by statistical test and then a forecast is extrapolated from this mathematical relationship.For example, we can forecast the fastest qualification (pole position) speeds at the Indianapolis 500 MileRace by plotting pole position speeds against time measured in years. Beginning with the post-World WarI races, the pole position speeds of Indy race cars have exponentially increased, Two technological
innovations are quite easily seen in the data. One is the rear-engine car. The first such car appeared in1961. Qualifying speeds were about 150 mph. In 1964 a rear-engine car won the pole position at slightlyless than 159 mph. The growth rate of qualifying speed is significantly higher with the rear-enginetechnology, so different exponential functions were fitted to front- and rear-engined cars.The second easily discernible technological innovation occurred in the early 1970s. It was the use ofsophisticated aerodynamic devices (wings at the rear of the car) to create down force on the cars, allowingthem much higher cornering speeds-from 170 mph in 1970, to 179 mph in 1971, to 196 mph in 1973(with the addition of wings at the front of the car).Limit AnalysisUltimately, all growth is limited, and there is an absolute limit to progress, either recognized or unrecognized.Sooner or later, projections must reflect the fact that improvements may get close to this limitbut cannot exceed it. For instance, a trend of increasing energy conversion efficiency cannot eventuallyexceed 100%. The trend of lower and lower temperatures is limited, of course, by absolute zero. (It isinteresting to note the rapid improvement in the ability to produce low temperatures that occurred around1900)