Does gun violence correlate with homicide more than all-weapon violence?

On my recent post I made a hypothesis and wanted to further investigate homicide rates related to gun violence. I hypothesized that gun violence is more responsible for homicide rates than violence in general. The basis of my hypothesis was comparing neighbourhoods, primarily in St. Louis and Winnipeg, which is a Canadian city. When we looked at the violence other than homicides, the Winnipeg's worst neighborhoods were a little bit worse than St. Louis's worst neighborhoods, being that they had higher sexual violence, higher robbery and higher major assault rates, but the neighborhoods in St. Louis had higher homicide rates. Here's a quote from that post: "of the neighborhoods in Winnipeg with an aggravated assault rate between 3000.0 and 3300.0, the average homicide rate is 81.8. In St. Louis, the average homicide rate in neighborhoods with such aggravated assault rates is 212.6, 2.5 times higher."

And my thought here was well, in St. Louis, there's a lot of gun usage. Whereas generally speaking, in Canada, guns aren't nearly as commonplace, and violent crime is often times carried out with a knife. For example, in Winnipeg, in 2020 and 2021, there were an average of 6 and a half stabbings per day. And so, my imagination was like, if those were 6 and a half shootings per day instead, that that would reflect in the homicide numbers.

Furthermore, the other day I ended up seeing a post on Reddit on the "data is beautiful" subreddit and it showed a couple of maps, and one of the maps was homicide rate by county and the other was poverty by county, or something along those lines. And so it tried to correlate these two factors together. And a lot of the comments said things like, "see, guns aren't responsible for violence!" and so on. So I really wanted to see if my hypothesis had some merit or not.

Data

Below is a table of the raw data I looked at. It's a really big chart. It's overwhelming to look at. So, I've broken it down into other tables with important information and we will go through them as this post progresses.

Note: you can view higher quality, PDF versions of all of the tables here.

Kill percentage

The kill percentage is the percentage of aggravated assaults with such weapon compared to the number of homicides with such weapon. So for example, the kill percentage by knife in Little Rock is 1.14%, that means that 1.14% of knife attacks resulted in the death of the victim. 

When we look at this with all fifteen cities' data added together, we find that the kill percentage of guns is 6.54% and it's only 0.82% for knives, 0.46% for clubbings (blunt objects) and 0.37% with hands. This means that guns are 8 times more lethal than knives. And this always the big comparison: guns vs. knives. Knives are 1.8 times more lethal than blunt objects and 2.2 times more lethal than "personal weapons", as they're called: whether that's choking something to death, stomping head, knocking them out and they hit the concrete floor, biting someone through an artery... that's personal weapons: I put "hands" on the short because it's shorter, but it really refers to this broader category. So knives are lethal compared to other weapons, but guns just blow the competition out of the water.

Assault by weapon rate correlated with homicide rate.

The next couple of things I looked at here were very interesting. I did two different metrics of correlation with homicide rates.

The first one I did was correlating the assault type per 100,000 residents to the homicide rate. With the assault type, we're just looking at the aggravated assault rates by weapon used. So for example in Sioux Falls, there were 131 aggravated assaults by gun, which gives us 68 shootings per 100,000 residents. So we're looking at the correlation between each of the assault types (shooting, knifing, clubbing and beating) with the homicide rate. We will also be taking a look at the correlation between total aggravated assaults and homicide.

To quantify correlation, I'm using the Pearson correlation coefficient. A score of 1.0 means a perfect linear correlation, so the closer to 1.0 the score is, the better the correlation is.

What we find here is that shootings correlate (0.86) a lot better with the homicide rate than total aggravated assaults (0.69). The correlation coefficient in isolation and without context isn't always informative or indicative of anything (Because what is a strong correlation? That depends on the broader context), but when we have relative comparisons like this, it's at least indicative in this comparative sense. It still does not tell the whole picture. For example, there might be other statistics that correlate with homicides more than shootings. For example, income level might also be a stronger factor. But at the very least, what this data suggests to us is that a homicide rate is more influenced by gun violence than violence itself, which is pretty staggering information.

It's probably a common assumption that places with higher shooting rates in general have higher aggravated assault rates, but that's not actually true. For example, if we look at Cincinnati, which has the highest percentage of aggravated assaults with guns, its aggravated assault rate is actually lower than a lot of these cities here: it's lower than Denver's, but its homicide rate is twice that of Denver's. It's on par with Portland's, but its homicide rate is also double Portland's. It's also pretty much on par with Des Moines, but its homicide rate is just way higher.

And if we compare with Buffalo, Buffalo's got an aggravated assault rate a bit higher than Cincinnati, but the shootings per 100,000 is quite a bit higher in Cincinnati, and as a result, Cincinnati's homicide rate is a bit higher than Buffalo's. 

Another example, if we compare Austin to Sioux Falls, Sioux Falls has a higher aggravated assault rate but Austin has twice the amount of shootings, and as a consequence, its homicide rate is a lot higher.


Assault by weapon % correlated with homicide rate

The next metric I looked at here was also really interesting. For this statistic, we're looking at the percentage of aggravated assaults by weapon. For example, in St. Louis, 58.6% of aggravated assaults used a gun, while in Salt Lake City, only 19.5% of aggravated assaults used a gun.

So this can vary a lot by city. I got data for 15 cities, I tried to get a nice diversity of cities, and it seems like I got that based on the variety in the statistics. We will correlate just this percentage with homicide rate. This isn't taking into account the aggravated assault rate at all, so theoretically a city here could have an aggravated assault rate of 300.0 but a gun percentage of 60% (= 180.0 shootings), while another city could have an aggravated assault rate of 1000.0 and a gun percentage of 35% (= 350.0 shootings). The latter city has more shootings per 100,000, but the gun usage percentage is a lot lower. So here, we're just looking at correlation between homicide and the gun usage percentage.

When we look at this, the correlation coefficient for guns is 0.8, and the other three weapons all negatively correlate, which means that the higher the knife usage percentage is, the lower a homicide rate we expect to see. This doesn't mean knives are safe, it just illustrates how lethal guns are. The higher knife usage percentage that a city has means that its gun usage percentage is going to be lower. This is why the other three weapons have negative correlations: because it implies a lower gun usage percentage.


Grouping cities by gun usage % and comparing with homicide

The last thing I did here was just a basic grouping. I made three groups based on the cities and their gun usage percentage One group is under 20%, the second is 20% to 40%, and the final group is 40% and higher. When we look at the average homicide rates in these cities, it looks pretty cut and dry: the higher gun usage percentage equals a higher homicide rate. 

On this chart, I also have the average aggravated assault rates. It is true that the average aggravated assault rate also goes up, but what is important here is that it's not to the same extent. For example, in the under 20% grouping compared to the 20-40% grouping, the homicide rate is 4 times higher, but the aggravated assault rate is only 1.2 times higher. And likewise, comparing the 20-40% grouping to the 40% and over grouping, the homicide rate is 2.6 times higher while the aggravated assault rate is only 1.8 times higher. So clearly the homicide rate is increasing more quickly than the aggravated assault rate as the gun usage percentage increases.

Outro: consequences and opinions

I'm not making the claim here that guns cause criminal activity or violence. If you read my last post, we saw that in general, the downtown's in Canada are actually more violent than the downtown's in the USA. In fact, if we excluded homicide rates from the violence scores, the most violent neighborhoods would be in Canada by a longshot. The USA does not have a unique crime or violence problem, it just has a unique homicide problem.


View my recent post to see sources and more data related to the above table.

I'm saying the data suggests that guns cause more violent conflicts to end up as homicides. 
Canadians, both criminals and private citizens, don't use guns as much as Americans. There are no stats in Canada based on assaults by  weapon used, but there are some interesting stats available that describe the same picture.

For example, in 2021: only 40% of homicides in Canada used a gun, while in the USA it was double at 79.2%. We already saw shootings correlating with homicides, so check this: in 2021, 2.4% of aggravated assaults end up as homicides in the USA, while in Canada, it was about 1.1%. Finally, in 2021, Canada's homicide rate was 2.06 while the USA's was 4.41. The USA is about double in all of these stats, so the correlation between gun usage seems pretty clear.

Did you know the gang homicide rate is higher in Canada than the USA? Canada's gang killings per 100,000 in 2021 was 0.48, 23% of its homicides. In 2021, The USA's drug-related and gangland killings was 8.0% of its homicides, which is 0.35 per 100,000. The USA does not have a unique gang problem. 

The consequences of this analysis is that, it speaks about one of the cons with having massive gun ownership. Contrary to popular belief perhaps, most homicides are actually not gang homicides, they're not drug related homicides, they're not homicides committed carrying out a robbery (6.0%), the vast majority of homicides in the USA in 2021, 50.9% of them, are just two people who get into a dispute, disagreement or argument. And that could be over a lot of reasons: it could be over a woman, over a financial situation, it could just be a general stupid disagreement, a fight that breaks out for whatever reason; fights break out for dumb reasons all the time. The point here is that: most homicides aren't related to prior felonious circumstances. So one might argue, "criminals will get guns anyways", but that doesn't take into account the circumstances of the majority of homicides.

And the consequence to this is, if you have a gun, or even just the fact that you live in a culture where you expect your opponent to have a gun, then you're going to draw that gun if you have access to a gun. And of course, if you want the biggest advantage, regardless, you're going to go for that gun. We've already see the kill percentage with guns is way higher than other weapons.

This clearly a massive con of having a very armed society. Now, I'm not here to debate gun control or gun culture. So just to be fair, because I don't want this post to be an anti-gun political post, because that's not my intention here, I'll say what I believe is the biggest pro to having a heavily armed society: the most vulnerable people are now able to defend themselves effectively: the gun is the greatest equalizer. And I think that's a good thing. But I also think that it's a bad thing that in a highly armed society that more violent conflicts are going to end up in death, because people are going to use guns on average a lot more in any given violent conflict.

In fact, going back to the political angle, it seems like most people are  talking about gun control in regards to mass shootings and gang violence, but I think that this is actually something that should be discussed a lot more. I think this is the bigger issue that needs to be discussed about having an armed society: more conflicts end up in murder. I often times people see, "well, without guns, they'll just get knifed instead", and it's like yeah well, look at the lethality of a gun vs. a knife. If you care about living, you'd rather get knifed than shot.

I just think it's important to have a clear picture on both the pros and cons of allowing or prohibiting certain things in your society. What are the pros and cons of legalizing marijuana? What are the pros and cons of legalizing harder drugs and having safe injection sites? What are the pros and cons of making alcohol illegal? What are the pros and cons of taxing sugar, or gas? What are the pros and cons of having an heavily armed society? Well, this post appears to describe one con.


Future research

I would like to see how income correlates with homicide rates and aggravated assault rates. But, I do not believe that this can or should be done at the city-wide level. I need neighborhood level data. There isn't much that city-wide data is useful for in regards to crime statistics in my opinion. For this analysis, it was okay because we weren't trying to determine how dangerous the areas are, we were just looking at general tendencies by weaponry. However, if we're going to compare income, well, just like neighborhood level crime rates within a city, the income profile of a city can vary a lot. Even if two cities have the same median income, that could just be because one city has a super rich 20% and a super poor 10% while the other city only has a somewhat rich 40% and a super poor 20%. 

Sources

Homicide in Canada, 2021: https://www150.statcan.gc.ca/n1/pub/85-002-x/2022001/article/00015-eng.htm
Purpose: To find Canada's gang killings and gun homicide %.

Police-reported crime for selected offences, Canada, 2020 and 2021: https://www150.statcan.gc.ca/n1/pub/85-002-x/2022001/article/00013/tbl/tbl03-eng.htm
Purpose: To find major assaults in Canada

FBI Crime Data Explorer: https://crime-data-explorer.app.cloud.gov/pages/explorer/crime/shr
Purpose: To find all of the data regarding crime in the USA and its cities in 2021.

Rash of long weekend stabbings part of grim trend, Winnipeg police say: https://globalnews.ca/news/8866156/long-weekend-stabbings-winnipeg-police/
Purpose: To find stabbing rates in Winnipeg

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