Dataset: trains.dat Source: E. Mansfield (1963), "Intrafirm Rates of Diffusion of an Innovation", The Review of Economics and Statistics, Vol 45, pp348-359. Description: Numbers of Diesel and Steam Engines among Major Railroads Bi-annually 1925-1959 Variables/Columns Year 5-8 Diesel Engines 12-16 Steam Engines 20-24