The basic principles of freight transportation demand forecasting are ( ).

The basic principles of freight transportation demand forecasting are the following three: ① principle of inertia. The process of change in objective things tend to show its continuity, usually called the phenomenon of "inertia phenomenon". According to this nature, the past and present state of the object of study, the continuation of the future, so as to predict its future state. The principle of inertia is the theoretical basis for trend extrapolation. ② The principle of analogy. Many things with similar characteristics, their changes have similarities, by analyzing the law of interconnection of similar things, according to the characteristics of past changes in things, inferring the future state of the predicted object with similar characteristics. Analogical inference can be divided into qualitative analogical inference and quantitative analogical inference. For example, using the transportation elasticity of place A at a certain economic level. To predict the transportation elasticity when place B, which is similar to place A, reaches the same economic level. ③ Correlation principle. Any thing development and change are not independent, but in the interaction with other things under the influence of development. The mutual influence between things is often manifested as a cause and effect relationship. The principle of correlation is the theoretical basis for regression prediction.