Constructing and using a multiplicative model of the impact of societal changes on violent crime

Abstract

This study aims at exploring the possibilities of using a multiplicative model when explaining the impact of societal changes on violent crime in Swedish municipalities. A theory of criminality in municipalities is presented which is founded on an analysis of individual decision-making on the commission of crimes. According to this theory, the level of criminality in a given municipality is determined by two average properties for the individuals who stay there — the average amount of occasions when the circumstances are favorable to the commission of crimes and the average probability of committing a crime on such an occasion. On the basis of the theory, a model of the relationship between criminality and specified characteristics of the municipality has been constructed. Criminality is assumed to be the product of a range of factors, each of which is a linear function of current and earlier values of a municipality characteristic. Using this model, the relationship between changes in the level of criminality and variables measuring independent characteristics at different points in time has been empirically analyzed. The data used are of register type and refer primarily to the years 1970, 1975, and 1980. Model parameters are estimated by a least-square fit. It is found that the multiplicative model explains much more of the variance in changes in the level of criminality than does the linear model including the same municipality characteristics. In the multiplicative model. independent variables obtain weights that give a different picture of the causal processes that affect criminality as compared with the linear model.