How to Evaluate the Safety of a City

摘要

Contemporary countries, with the rapid development of technology, productivity and the rapid development of the society, is beginning the industrial society and information society evolution from industrial society. In this process, there have been serious class differentiation and conflict of interest, the type of crime is undergoing significant changes. Since the development of industrialization and city, violent crime is much higher than that of property crime. At the same time, with the advance of that, property crime has become the mainstream, and showed a sustained growth trend. Crime in the city is a major factor that threatens the urban safety. So it will be meaningful if an effective method can be developed to help evaluate how safe a city is. In this essay, create two math models to tackle this problem. First of all, if we have some data of crime events, we can find out the related factors that affect the safety of the city based on the index system. Then a multi-level evaluation index system is formed, which consists of object layer, criterion layer and decision layer. In model one, we set up a Principal Level Analysis Model in order to calculate the weights of various factors. Above all, we establish the judgment matrix of each element, according to the link between the elements, and figure out the value of this matrix. Then the weight value of each element in the criterion layer and decision layer is obtained by means of AHP Method. In model two, we establish a Fuzzy Appraisal Model, which is an important approach to the quantitative analysis of city safety. To begin with, we set up evaluation sets, and then the subordinate degree of each index can be constructed. Finally, we calculate the comprehensive evaluation matrix, which can specify a measure of how safe this City is.