A robbery is not the same as a murder: Why the United States needs better crime statistics

President Donald Trump has long been focused on Chicago as the focus of American crime. This was again raised on October 8, when he stated that he had asked the Department of Justice to work with local authorities in Chicago to end the violence in a city overwhelmed by its rate. high level of violent crime.

With 24.1 homicides per 100,000 population – more than four times the overall rate of the United States – Chicago suffers from serious problems. But since September 25th, the FBI considers that St. Louis, my hometown, is the most dangerous city in America, with more than 6,461 violent crimes reported within the city limits in 2017. This represents a increase of more than 7% over the previous year. year.

In the United States, St. Louis is only the third country in terms of homicides, but it is the most dangerous city in the world. So, by what metric does the government measure the "most dangerous" – and why does Trump focus on Chicago and not on St. Louis? As a statistician studying how people can handle numbers, especially crime data, it's clear that the way crimes are currently accounted for in the United States can easily confuse and mislead .

Crime statistics

Since 1929, the FBI has managed the Uniform Crime Reports (UCR) program, a project that compiles official crime data from the United States, provided by smaller law enforcement agencies. For example, in Missouri, data is provided directly to the state by both county police departments and small municipalities. This information is then sent to the FBI.

With 18,000 different law enforcement agencies providing crime data to the FBI, there must be a standard reporting indicator. All crimes are therefore classified in only two categories: Part 1 and Part 2.

Part 1 crimes include murder, rape, robbery, robbery and arson – serious crimes. Part 2 crimes include common assault, waiting, embezzlement, DUI and prostitution – the least serious crimes.

Ok, that makes sense. But here's the problem: none of these crimes are weighted. When a "handsome innocent 9-year-old who was lying on the bed doing his homework" is murdered in Ferguson as a retaliatory murder, it has the same effect as when a person is arrested for theft above $ 50 per dollar The store. This imperfect metric allows for incredible confusion.

Take this example. You live in a nice neighborhood with a kmart edge. The "serious" crime includes all the stealing of the Kmart; Say 150 incidents in a year. This also includes all murders and rapes; call it 20 incidents in a year. The Kmart closes. All of a sudden, your crime rate went from 170 to 20: an 88% decrease in crime.

Chicago Mayor Matt McGrath's spokesman criticized Trump's comments to the Washington Postsaying, "Just last week, [the Chicago Police Department] reported that there were 100 fewer murders and 500 gunfire victims in Chicago this year, the second consecutive year of decline. And really, I did the math; all serious crimes have only increased by 6.88% since 2014.

But it's not the serious crimes that make me look under my bed before going to bed at night. These are violent crimes. These increased by 24.27% in Chicago between 2014 and 2017. The number of murders increased by 59.53%. (Researchers are still trying to understand the cause of the rise.)

This metric can be misleading. Former St. Louis Mayor Francis Slay speaks of "small gains" as the total number of criminal acts decreases. Admittedly, the number of Part 1 crimes has actually decreased by 0.4% since 2014. However, violent crime in the city of Saint-Louis has increased by 24.04%.

People can also be confused by the way crimes are cut geographically. For example, in 2016, the city of St. Louis had a homicide rate of 59.8 per 100,000 population, while St. Louis County, separated from the city by a street, had a homicide rate of Homicides of about 3.2 per 100,000 inhabitants. What combination of the two that make up the Greater St. Louis is reported in the news? Depends on the day.

New measures

Here's what I know: the United States needs a better measure. Our way of measuring crime has been controversial since the publication in 1929 of the FBI's initial report on crime.

There are even problems with the count itself. The FBI website removed data from Chicago crime statistics in 2013 because the FBI felt they were under-reported.

Let's hope that the FBI's national Incident-based Reporting System, due to be rolled out in 2020, will enter into a more accurate metric. For example, if a criminal assaulted a person from his home and stole jewelery, it only counted as an assault within the meaning of the law. UCR system. Under NIBRS, aggression and theft would be counted.

But this system does not seem to answer the key question: weights. Murdering a child can not count as much as flying in the dollar store. It is inconceivable that raping someone can count as an illegal game. You are serving different prison sentences depending on the seriousness of the crime. Why should not crimes be equally weighted?

Cities like Chicago and St. Louis certainly have crime problems. But how US "dangerous" measures need to be clarified. It hurts our police and our communities by allowing this false representation of the facts. Until then, politicians can use this confusion to confuse the public, intentionally or not.

Liberty Vittert, visiting assistant professor of statistics, University of Washington at St Louis.

This article is republished from The Conversation under a Creative Commons license. Read the original article.