The variables are:
Yr |
| year of first manufacture |
Period |
| a code to indicate one of three broad time periods |
Power |
| total engine power (kW) |
Span |
| wing span (m) |
Length |
| length (m) |
Weight |
| maximum take-off weight (kg) |
Speed |
| maximum speed (km/h) |
Source: The data were collected by P. Saviotti and are described in detail in Saviotti (1996), "Technological Evolution, Variety and Economy", Edward Elgar: Cheltenham.