Industrial agglomeration of urban agglomerations

There are many methods for calculating the level of industrial agglomeration. The representative methods are the structural similarity coefficient method proposed by the International Industrial Research Center of the United Nations Industrial Development Organization, the Krugman Specialization Index proposed by Paul Krugman, structural coincidence index proposed by Finger and Kreinin, and location entropy method, etc. Among them, most studies believe that the Krugman Specialization Index method performs best in measuring the level of regional industrial agglomeration. Therefore, this paper also uses the Krugman Specialization Index to measure the industrial agglomeration of urban agglomerations. The calculation formula is as follows.

Where IA_ij is the industrial agglomeration level of the r-th urban agglomeration (Krugman specialization index, which is the average value of the industrial agglomeration level of each city in the urban agglomeration); m is the number of cities in the urban agglomeration, k is the number of industries, and k = 1,2,3…,n; X_ik is the proportion of the number of employees in the k-th industry in i-th city to the number of employees in the entire industry, and X_k is the proportion of the number of employees in the k-th industry in all cities in the urban agglomeration to the number of employees in the entire industry in all cities.