The quality of statistical information on domestic transport in Britain is uneven. Figures on all forms of rail transport and on road passenger transport are based on detailed annual returns and are relatively reliable (although some doubts have been expressed about the accuracy of the returns made by some bus undertakings). Figures on road goods transport and on private passenger transport are based on much less secure foundations . Estimates of road goods traffic depend on sample surveys made by the Department of the Environment.1 The last survey on which current information is based was carried out in 1968, though more recent data are just becoming available from a survey made in 1971. Figures based on these surveys contain two main possible sources of error. The Ministry surveys are samples, so that there is the chance of sampling errors, and figures in other years are based on possibly misleading projections of the sample data. A general difficulty of transport statistics is that there is no homogeneous unit of output that can be measured. The units most generally used are passenger miles and ton miles, but, as Bayliss and Hebden have demonstrated , these suffer from the disadvantage that they may not reflect accurately the resources used in different transport operations.
KeywordsNational Income Road Transport Rail Transport Passenger Transport Secure Foundation
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