On the basis of the principal component analysis, this paper deals mainly with the areal production system of agriculture in Northwest Shandong Province.The relative matrix, eigenvalues and principal components of the constitutional variables of the system are given in Table 2-4. The first principal component can symbolically be regarded as the "input-output principal component", the second one as the "plantation principal component", the third one as the "grain production principal component", and the fourth one as the "industry and sideline principal component".In order to reveal the areal differentiations of the agricultural system in Northwest Shandong Province, a classification of the areal system has been carried out (Fig. 1) according to the marks given by the first principal component of the different areal units (Table 5).
