Which homicides decreased? Why?

• Author: Maltz, Michael D.

In a sense, criminologists are luckier than economists. Economists are asked to forecast what will happen to the economy, and a lot of them get it wrong. Criminologists are asked to back-cast, to explain what happened after it happens, and probably with about the same success as economists have at forecasting: even though we know what the outcome is, we often don't know why. But this is not for lack of trying.

After reading the papers and hearing the presentations, I am struck by the care with which the authors have analyzed the homicide data at three levels: national, multi-jurisdictional, and single-city. My comments should in no way be seen as criticisms of their efforts; rather, they are suggestions as to additional steps that might be taken. My comments focus on two areas: disaggregation of homicide data, and considering whether "regression to the mean" might explain the recent decline in New York City homicides.

1. DISAGGREGATION.

   As Frank Zimring pointed out in his remarks, these three papers go from the general to the specific. The first(1) discusses time trends for the whole country, the second(2) focuses on eight cities, and the thirds is limited to one city. But I think that even more disaggregation is necessary in trying to understand homicide trends.

   Homicide is a crime in and of itself; but in another sense it is the fatal outcome of a many different crimes.(4) Child abuse is a crime, and when it turns fatal it becomes infanticide. Domestic abuse is a crime, and when it turns fatal it is homicide among intimates.(5) Armed robbery is a crime, and when it turns fatal it becomes a felony homicide.(6) I would like to see studies that look at trends in child abuse, domestic violence, and armed robbery--as well as other offenses-and see the extent to which they are related to the trends in homicide: for example, since most infanticides are not committed with guns, perhaps a long-term decrease in child abuse is the cause for the long-term decrease in non-gun homicides that Fagan, Zimring, and Kim noted.(7) To understand a phenomenon, it is usually necessary to go to the next level, to understand the context in which the phenomenon is found. Looking only at homicide statistics begs the question of the many different motivations that may be driving the statistics. Knowing the authors of these papers, I am sure that they are well aware of this, but the readers should be cautioned that additional steps need to be taken to provide a greater understanding of homicide.

2. REGRESSION TO THE MEAN.

   The three homicide studies to which I am responding(8) all used homicide data from the FBI's Uniform Crime Reports (UCR)(9) and Supplementary Homicide Reports (SHR),(10) or arrest data from the UCR; that is, all used data that were obtained from the police. It turns out that victimization data-data about crime obtained from victims-can also be used to explore at least...