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APRIL 20, 2012 10:53AM

Added Homicides: More evidence against “Stand Your Ground”?

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In my previous post, I examined the effects of the "Stand Your Ground" law on the number of justifiable homicides in the State of Florida. For this, I conducted a simple before-after analysis using data reported in the Tampa Bay Times. Despite the limitations associated with these data, the results seemed to show that the number of justifiable homicides increased significantly following the introduction of Florida Statute 776.013 (3) in 2005.

I decided to dig a little deeper on this subject. I was specifically interested in finding out whether or not the SYG law influenced the total the number of homicides covering the same time period I used in my first post. Not only was I able find the data I needed, but I was also able to uncover similar data for the entire country. The national data can be used to refine the predicted number of homicides by accounting for spatial and temporal variations (e.g., changes in the economy, policies affecting a large portion of the population, weather patterns, etc.). I won't repeat the study methodology and terminology here, but the avid reader can found them in the original post.

Using the Florida Department of Law Enforcement (see here) as well as the FBI (see here) websites, I extracted data on the number of homicides, the number of homicides involving a firearm, as well as the number of violent crimes. I decided to include those because one person who commented on my first post indicated that the SYG law could potentially influence violent crime rates. We'll see later if this is the case.

But first, let's examine the number of homicides, shall we?

The table below shows the number of homicides between 2000 and 2010 for Florida and the United States: 

figure 1
 
A preliminary assessment of this table seems to show a spike in homicides between 2006 and 2009. One attribute that may not be obvious, however, is that the proportion of homicides involving a firearm increased from about 59% in the before period to 67% in the after period (a change that is statistically significant). This change in percentages will become very important below.

As discussed in the first post, the data are better illustrated using figures. The first figure shows the number of homicides for Florida, while the second one focuses on the homicides that occurred at the national level.

figure 2
  

Annual Homicides in the State of Florida (Source: FDLE)

Figure 3


Annual Homicides in the United States (Source: FBI)

The first figure shows that the annual number of homicides initially increased substantially between 2005 and 2007, but also decreased rapidly between 2007 and 2009. The homicides involving a firearm followed a similar pattern.

Interestingly, the same characteristic can be seen with the national data. However, in this case, the number of homicides starts increasing in 2004, but peaks in 2006 rather than in 2007. The decreasing rate is actually greater than the one observed in Florida (this is difficult to see on the figures).

In short, since a similar variation can be discerned in Florida and the rest of the U.S., a portion of the trend observed in the homicide rates in Florida can also be explained by factors influencing the murder rates for the entire country.

The question becomes: "How does the national trend affect the number of homicides in Florida?"

To answer this question, I again performed a before-after study for your benefit. This time, I conducted two analyses: with and without the national data. I removed the Florida homicides from the national data for the second analysis. We don't want to duplicate the counts, right?

The results for the total number of homicides are shown below:

figure 4
 

Before-After Analysis for the Total Number of Homicides in Florida

The figure above illustrates that the national trend had a large impact on the total number of homicides. The observed increase changes from 22% (statistically significant) to about 2% (non-statistically significant). Overall, the analysis shows a marginal increase in the total number of homicides for the after period. Weird, isn't? There is probably a good reason, which I'll address at the end.

Now, let's look at the homicide data involving firearms.

The results are shown below:

Figure 5
  

Before-After Analysis for the Number of Homicides Involving a Firearm in Florida


The figure above demonstrates a much more clear-cut increase in the number of homicides involving a firearm. The national trend reduces the observed increase by about half, from 38% to about 17% (both being statistically significant).  Although a very small increase was noted for the total number of homicides, a larger increase can be noted for those involving a firearm.

As noted above, the proportion of homicides caused by a firearm increased substantially in the after period. In this regards, it is important to note that the SYG law is strongly linked with the use of a firearm (concealed weapons). Thus, the observed increase in homicides caused by a firearm may not be surprising. Interestingly, CNN reported yesterday that the State of Florida intends to review its gun laws following the Trayvon Martin tragedy.

Again, there is definitely something that happened in 2005, which  changed the characteristics of homicides in Florida.

Putting aside the homicides, let's focus on the violent crimes.

The raw data for Florida and in the U.S. are presented in the two figures below:

figure 6


Annual Violent Crimes in Florida (Source: FDLE)

 

figure 7
 

Annual Violent Crimes in the United States (Source: FBI)

Both figures show a similar tendency: a small decrease ending in 2004, followed by an increase peaking in 2006/2007 before coming down again. Using these data in the before-after study shows a small decrease of 5% (statistically significant) in violent crimes. However, when the national data are included in the analysis, the decrease becomes equal to a mere 2% (not significant). Including the national data indicates that the reduction in violent crimes observed in the U.S. is actually greater than the one noted in Florida.

What do these analyses tell us?

Well, here are my concluding points:

  • Accounting for the national data, the SYG law in Florida seems to be associated with an increase in the number of homicides involving a firearm, although the total number of homicides didn't increase significantly after 2005. The increase may be masked by a reduction in non-firearm-related homicides, which could perhaps be attributed to a national trend. The magnitude of the increase is more or less in line with the increase in justifiable homicides discussed in the previous post.
  • The reduction in homicides and violent crimes after the peak seen in 2007 is smaller in Florida than the decline noted at the national level.
  • The SYG law doesn't appear to have reduced the number of violent crimes in Florida (marginal at best).

Obviously, further work should still be done to examine these issues more closely. If someone pays me, maybe I'll look into them.

The usual caveat: other unknown factors combined with the SYG law could also be linked to the increase in homicides caused by a firearm. (We always need to write this kind of warning in our research reports and papers.)

There you have it, folks! Free of charge for your edification.

I know this was a long post. Sorry...

Update (April 22, 2012)

New post: "Stand Your Ground": How does it stand up to history?

 Update (June 9, 2012)

When I conducted the analyses above, I didn't include the changes in exposure (i.e., population) between the before and after periods. First, I did not have access to the data at the time. Second, we do not know whether the relationship between the number of homicides and exposure is linear.  When it is linear, we call this a 'rate' (e.g., homicide rate). However, it's possible that the relationship is not linear, which is very common with other datasets.  The changes in population are shown in the table below.

Figure 8

  (Source: http://www.disastercenter.com/crime/uscrime.htm)

This table shows:

  • The population increased by 9.2% between both periods (average for each period).
  • The largest increase occurred in the before period.
  • The number of people in Florida almost remained flat in the after period.
  • If we account for the changes in population, the increase in all categories of homicides cannot be attributed solely to the increase in population.
  • This means that other factors are at play.

 

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Bottom line: "The SYG law doesn't appear to have reduced the number of violent crimes in Florida (marginal at best)." And I appreciate the nuanced nature of the conclusion. All three bullet points add to the discussion of the effects of the law. Some of us simply want facts and analyses we can trust. I, too, want somebody to pay you to publish your work, which goes far beyond what so many bloggers do.
Thanks, Steve! The kind of stuff I did above could lead to an official publication. Took a while to wrote.
That's the real question, as re-classifying would have that effect always. Need to read very carefully as to whether or not I concur, but that's nice of you to explain how that is done.
It is also of course only one consideration, although the Common Law had a duty to retreat in Eastern states until recently, as to another way of looking at the problem as to the role of law being to impart stable expectations more than anything else.
Don: Thanks for your comment. I'll let others who know about how these laws based on Common Law are applied comment on this subject.
The whole idiotic notion espoused by second amendment/NRA wingnuts is that we will all be safer if everyone walks the streets armed to the teeth. Leaving aside logic, since it is of no use with these people, aren't the at least aware of how lawless was the Old West, a place where life was indeed often "nasty, brutish and short".

And if Hobbes can't convince them, how about Dirty Harry? Anyone who's seen Eastwood's "Unforgiven" should have a pretty good idea that frontier "justice" was seldom meted out in a duel in the sun on main street. Why drawn down on some facing you twenty feet away when you can wait till later and shoot him in the back?
STOP!!!! STOPPPIT!! PLEASE!

You're confusing gun-nuts with facts and logic and you're gonna make their heads explode. Then we'll have a huge mess to clean up, dammit.

Very nicely done, Kanuk
Yes, but is that the only thing that happened? And what about the other statistics? There was a decrease in forcible rape, particularly when the attacker had a firearm. Could the SYG law be responsible for that, too? What about for the 60% decrease in stalking or the 15% decrease in forcible sodomy?

Statistics are fine and all... but numbers without context are just numbers. Correlation != causality.
Much more significant than SYG was the "Right to Carry", since most of these homicides (that were not drug related) were home breakins, etc. Were you aware that there was a very detailed academic study about all this, focussing on the RTC over a period of generations, and covering every county in the US? It's (sensational) title was "More Guns, Less Crime" by Prof. John Lott. This was not just a top-of-the-head effort, either, though the title about sums it up.
shawn disney:
I remember when the C&C law went into effect in Florida. It did give criminals pause... unfortunately, it also made targets of tourists, since they were less likely to be carrying. Tourists were easily identified by having rental cars, which back then all had license plates that started with Y or Z.

From my perspective as someone who lived & worked in South Florida, things sure did get more polite. ;)
Tom Cordle: Sorry, you doing a lot of Monday morning quarterbacking, and using Hollywood as a source is not very convincing. The whole idea that the West was "Lawless" was very exaggerated, and the idea that men were often killed Mafia style is not accurate. There were certainly "duels", but no one got points for shooting people in the back; sometimes an opponent would be provided with a gun if he didn't happen to have one handy. Furthermore, a lot of the action happened in a mere one generation or so in time, and was rather specialized , being boom town drunks on Holiday; most people were too busy working to participate. In fact, it is a kind of measure of how untypical it was , that people still talk about Northfield, or Dodge City. Not much of modern entertainment in those days.
Interesting numbers, but I'm not sure what they mean. I can understand how SYG could increase the number of justifiable homicides. But how SYG would increase the number of murders is a mystery to me. Sometimes numbers have a coincidental relationship. In noticed that one state, Massachusetts, had an increase in the murder rate during the same period, but they don't have an SYG law. Arguing that SYG is related to the number of firearms homicides has a kind of "post hoc ergo proper hoc" feel to me.

If you go back a couple of decades, you see that the number of murders in Florida is returning to around the same level that it was in the 1990s. (Although the murder rate has dropped because the population has increased.) So this makes me wonder if there is some kind of weird cyclical thing going on. I also noticed that Florida circuit court criminal filings increased by 20 percent from FY0405 to FY0708 -- and then decreased by almost the same amount between FY0708 and FY0910 -- which I don't get either.

So it's hard to know what to say. Sometimes numbers are just strange.

By the way, congratulations on the cover. Can the Second Coming be far behind?
Tom: That’s an extreme analogy, but you’re more likely to see something like that here than up north for example. Trayvon’s death’s comes close to it.

Boomer Bob: Thank you!

Susan: Thanks for your comment. I indeed understand the difference between correlation and causality, which explains why I never used the word “causation” above. Some of the points you’re raising, such as for forcible rape and sodomy are included in the violent crimes described above. If we reduce some type of crimes, but increase others in the process, we’re not better off. I’ll let other people examine this issue.
Shawn: The research on this topic is very extensive. It is important to look at entirety of the literature, not just one single book. Here are some examples:

Gun availability and violent death. American Journal of Public Health v. 87 (June 1997) p. 899-901:

The relationship between the availability of guns and violent death is discussed. In this issue, Cummings et al. report the findings of a case-control study to estimate the effects of handgun ownership on a family member's risk of suicide and homicide in a large health maintenance organization population for the period 1980-92. The results, which agree with the findings of other epidemiological studies involving different populations and techniques, indicate that owning a handgun or having a family member who owns a handgun significantly increases the risk of violent death. When all the confounding factors are accounted for, the results of Cummings et al. indicate that although it may be in the interest of particular individuals to purchase a gun to protect their families, it may not be in the interest of society for every family to purchase a gun. Although epidemiology cannot settle the political, ethical, and philosophical dilemma between the individual and society, it can enhance our understanding of violent death and how to prevent it.

Hoskin, A. (2011) Household gun prevalence and rates of violent crime: A test of competing gun theories. Criminal Justice Studies 24 (1), 125-136:

This study analyzes the reciprocal relationship between a direct measure of gun availability and three types of violent crime across the 120 most populous counties in the USA. Survey data from the Centers for Disease Control and Prevention's Behavioral Risk Factor Surveillance System are used to construct a measure of household gun prevalence. Hypotheses derived from four competing perspectives concerning the role of guns in the production of violence are tested. Strong support is found for the view that easy access to guns raises the risk of serious violence by giving the perpetrator the power to inflict greater victim injury. By contrast, no support is found for the argument that widespread legal gun ownership lowers violent crime by deterring prospective offenders.

Duggan, M. More guns, more crime (2001) Journal of Political Economy, 109, pp. 1086-1114:

This paper examines the relationship between gun ownership and crime. Previous research has suffered from a lack of reliable data on gun ownership. I exploit a unique data set to reliably estimate annual gun ownership rates at both the state and the county level during the past two decades. My findings demonstrate that changes in gun ownership are significantly positively related to changes in the homicide rate, with this relationship driven entirely by the impact of gun ownership on murders in which a gun is used. The effect of gun ownership on all other crime categories is much less marked. Recent reductions in the fraction of households owning a gun can explain at least one-third of the differential decline in gun homicides relative to non-gun homicides since 1993. I also use this data to examine the impact of Carrying Concealed Weapons legislation on crime, and reject the hypothesis that these laws led to increases in gun ownership or reductions in criminal activity.
Mish: Thank you! Well, often with these kinds of data, we try to estimate whether a change in the number of events (deaths, motor vehicle crashes, etc.) occurred if we know some intervention happened at point in time X. If we find such change (sudden and detectible increase or decrease), we then look more closely at the data. Sometimes, we may examine each case individually, which can be very time consuming.

I was actually talking with a journalist about this piece when you posted your comment. He was telling me that, in Florida, there has been a huge increase in people seeking a concealed weapon permit since 2007 or so (because of Obama). Maybe this could be one of the factors. As I mentioned at the bottom, more detailed analyses should be done to explain what we observed.
Shawn Disney
You're last name says it all -- you really believe rontier justice was handed out like in John Wayne movies, huh? So what's your take on Unforgiven? Reality or hyperbole?

By the way, I base my opinion at least partly on where I live -- the mountains of East Tennessee -- where for many people "lawing" somebody is still considered a no-no, and where disputes are often still settled with guns. Admittedly, many if not most of those disputes involve alcohol or these days meth. Drugs ain't just a problem in the big cities, and per capita Monroe County probably ranks right up there with Trenton or a number of other big cities I could name.

Of course, that's not a scientific conclusion based on statistical analysis -- it's mostly based on reading the local police blotter newsrag -- and ducking.
At Common Law, one has a duty to retreat, to not breach the peace with lethal force in particular, unless "pushed to the wall." Caselaw in Eastern states followed this pattern, if out West, not, Tom's Wild West hypothesis being correct.
Thus, as to justifiable homicides increasing, that was totally predictable, as was the intent in part, to make sure that some people didn't go to jail who did under the other statute. Of course, that is like a TypeI-II error issue, as to now, some people getting shot and the shooter not being punished who "should be."
Me personally by the way, I don't mind guns, and like shooting them, in certain settings where that makes sense, if not a "gun nut."
I agree with Steve that this deserves publication - and being brought to the attention of legislators.

As for me, I think it's common sense that SYG is going to produce more deaths. That having the country awash in guns is going to do the same. And that the NRA are loons.

However, neither common sense nor charts&figures have much influence on the scared and the looney.
Tom: You seem to live a very "dangerous" place... Hopefully, they don't shoot and kill young mothers to steal their 3-day babies, as it happened north of Houston two days ago.

Don: Thanks for the additional information.

Myriad: Thanks to you too and have a safe trip back home.
I probably ought to leave bad enough alone, but it's not in my nature. For the record, I've owned guns including a 12-guage shotgun and a .308 Winchester. I've shot and killed a deer, after all I am male born and raised in Michigan. But I sold my guns long ago, and I haven't hunted in thirty years or so. I have nothing against guns per se, but I see NO reason reasonable gun control laws shouldn't be passed and enforced.

For starters, I believe every handgun sold in the US should be fired and tested, and it's rifling pattern kept in a Federal database. I see no reason that flea market gun sellers shouldn't be subject to the same strictures as retailers. And I believe thirty-round clips should be banned and selling or owning one should carry a stiff fine and jail term. According to the NRA, that makes me some sort of terrorist.

As for where I live, I'm not suggesting our tiny town is someplace one is afraid to walk the streets at night -- it's definitely not, and that's one of the reasons I chose to live in a place so remote. What I'm trying to say in my usual inarticulate way is the people imagine such places are bucolic, pastoral near-paradises. They're not.

Such places have an underbelly of violence which mostly remains hidden -- until it explodes. This is a place where someone can be killed or badly beaten over a perceived insult or a misinterpreted glance. It's a place where people are willing -- and admired -- for taking the law into their own hands. It's a place where guns are worshiped with same sort of fervor as the Bible -- in that, Obama was exactly right -- tho probably not too politically wise to speak the truth.

I find worship and weaponry to be particularly troubling among people who claim to be Christians. It's as if they've never read the red letters spoken time again by the Prophet of Peace who founded the faith they claim.
Kanuk writes: "He was telling me that, in Florida, there has been a huge increase in people seeking a concealed weapon permit since 2007 or so (because of Obama). Maybe this could be one of the factors."

I've had a concealed handgun permit for almost 16 years. So I look this issue from the point of view of someone who carries a licensed handgun all the time.

First, in order to get a CHL (in my state) you have to take a class, get fingerprinted, and go through what appears to be a fairly comprehensive background check. Anyone with a criminal record will not get a license.

In addition to the basic class, many CHL holders take additional classes on the legal aspects of the use of force in self-defense. In addition, there are a number of books on the topic, and several gun magazines regularly publish articles on the topic.

What becomes clear very quickly is that if you make an error of judgment in using lethal force in self-defense, you can very easily end up in prison. And even if you do everything right, you can still end up being prosecuted and spending your life savings on a legal defense. The consequences are so dire that it makes sense not to use a handgun in self-defense unless you really have no other reasonable option.

So I have a hard time understanding how an increase in handgun licenses would create a rash of murders in Florida -- how people with no criminal background would suddenly decide to become felons. That has not happened in any other state as far as I know. It certainly hasn't happened where I live.

When I look at those numbers, I'm baffled. I don't get it. I see the numbers, but I'm unable to explain them.
Tom: Thank you for providing additional information about where you live. Very interesting.

Mishima666: Thanks to you too about describing the process to get a license to carry a concealed weapon. Greatly appreciated.

Indeed, the numbers are puzzling. Here are my thoughts on this:

First, with the new SYG law, many people who carry a licensed weapon may be more inclined to use deadly force if they feel threatened knowing that they may not be charged if he or she kills the perpetrator. We have a good example with George Zimmerman. According to the links I put on my previous post, the number of people who claimed that they justifiably killed someone in self-defense significantly increased after the law was introduced. Not all of them will be "approved" so-to-speak by the DA's office.

Second, if you have more people who hold a concealed weapon permit and own firearms, greater is the risk for a weapon to fall into the wrong hands. As described in the U.S. Department of Justice website, about 80% of inmates who used a firearm obtained it illegally or through a friend and family member. In one recent shooting (I don’t recall which one), the teenager “borrowed” the (legally obtained) gun from his uncle when he went on a shooting rampage at his school.

I have seen many news reports where I live about people having their house broken into and their weapons stolen. In fact, over the last year, at least two gun shops were broken into in the middle of the night. In one case, more than 200 firearms were stolen.

With regards to the former, I remember an incident that happened in Canada (we do have guns, but it is strictly regulated). The uncle of a former friend of mine was an avid gun collector and one day someone broke into his house when he and his family were away. The only items missing were his firearms that were locked in a cabinet (not even the jewelry was taken). The culprits were found when someone called the police anonymously. It turned out that the kids who stole the guns were actually neighborhood friends of his teenage son and had previously been in his house. Thus, these kids knew where the guns were in the house and when the family was away (hence no risk to be shot).

Third, although most gun owners are responsible people, there are still many who can snap at any time, especially in cases of domestic dispute. The sister of a friend of mine was killed by her husband who legally owned firearms (before killing himself). This happened year or two after I moved here. Not only did the husband kill his wife, he did it right in front of his two young children who saw everything with their own eyes (if I remember correctly). Since then, I have also met a few friends and acquaintances who shared with me similar stories about friends and family members who suffered the same fate at the hands of their loved ones (via a firearm).
"I have seen many news reports where I live about people having their house broken into and their weapons stolen"

The only thing this statement, and I'm guessing most of your numbers, prove is that people who don't care about the law will commit a criminal act to steal a weapon or even kill someone.

Crazy people? Same thing. If they snap and decide they are going to kill their spouse or their self and a gun is around so they use it. What makes you think if there isn't a gun they won't use a knife or a rope or what ever else they find? If you check I'm willing to bet that you will find that more people try to kill themselves with drugs than guns. They just get better results with a gun.

Could be why the saying, Figures lie and liars figure seems so true.
No increase in homicides but an increase in justifiable homicides after SYG points directly to SYG as the cause, as the increase could not be attributed, in a significant way, to a sudden surge in incidents that would have been justifiable under duty to retreat.

To argue otherwise is to seek cosmic wave influence or a something-in-the-water cause. Increase in full Moons?

In my limited experience, the few I've known with CC permits were ultra-responsible people. The exception, though not in a criminal way, was crazy Pat and his wife Minnie. He had a machine gun permit, and were both truly gun fanatics. They lived in the country and were known to shoot at roaches and spackle the holes as needed.

I'm betting mishima is one of those ultra-responsible types, but as states loosen qualifications for permits and the number of permits grows large, the number of irresponsible permit holders also grows. Getting the permit becomes more popular as well--more are motivated to do so. The ratio of responsible/irresponsible doesn't necessarily change, but the added number of irresponsible people would probably become reflected in the statistics at some point.

That's speculation, but still a logical scenario. That the SYG law is a direct influence on the rise in justifiable homicides is about as close to carved-in-stone as it gets.

Good stuff, Kanuk, and congrats on getting E-Peed upon.
catnlion writes “If they snap and decide they are going to kill their spouse or their self and a gun is around so they use it. What makes you think if there isn't a gun they won't use a knife or a rope or what ever else they find?

Everyone has an opinion, but not everyone understand the facts. You can start learning about them here:

The Facts on Guns and Domestic Violence

When Men Murder Women: An Analysis of 2009 Homicide Data

Domestic Violence and Firearms

I remember reading more research studies on this topic, but I don’t have the time to look for them.

Paul: Thanks a lot! I'm sure that a large proportion of people who own firearms are responsible. However, even if we have say 5% or 10% who don't, their behavior can have drastic consequences, as we have seen with George Zimmerman.
You want your info read. Great, now give info that proves your point. In the first piece it says "54 percent of female homicide victims were shot and killed with a gun".

What this says is if someone wants to kill you they are going to find a way to do it. It also shows that guns work well, but all the other ways of killing you will work.

Let's look at how many women people tried to kill, not just how effective they are. I'll bet that if the number one way to kill women is to throw them off a 20 story building it would show that it's almost always works. By the same token getting shot in the head almost always works. It doesn't prove that anything.

All this proves is people with guns who want you dead will make sure it happens and don't care about the mess it makes. Guns will make it happen.
You did a lot of research but appear to either have ignored the key metric: how many murders using firearms were committed by criminals and/or were found to be criminal.

It could simply be that criminal activity increased in Florida for whatever reason and these criminals decided to use guns to murder people.

It could even be that without stand your ground there would have been more murders.

Until you account for the missing data as mentioned above your analysis is meaningless.

You use terms like " strongly linked" and "observed increase" however in a statistical analysis these terms are meaningless but sound "pseudo scientific."

Were I your teacher I'd have to give you a solid "D" for this "report."

Lastly, the Florida economy has been hit much harder than most due to real estate and it could be this is why crime has increased. Point is, nobody knows and your article doesn't really shed light on it, either.
Interesting statistics. Two ways to look at it. One is the increase of homicides the result of SYG or is SYG the results of increasing homicides in Florida. While major cities in Florida have seen a increase in population Jacksonville 11% Orlando area 25% and Miami 10% since 2001 the crime rates has not increased in proportion to the increased population. Florida ranks 24th with 11.5 gun deaths per 100,000 DC has 31.2 per 100,000. Florida has conceal carry and SYG, DC does not. Florida population is the 8th fastest growing state yet ranks 24th with a 40 year low in crime.

If there is to be any cause and effect for SYG. The question to ask how many of the homicides are a result of SYG or how many shooters have used it as their justification? And of those who use SYG defense how many after investigation were found not to be justified?

As an average citizen I am not as worried by criminals shooting each other during a criminal enterprise or victims shooting criminals in self defense. The only issue for me is how many innocent people have been shot unjustified by non-criminals because of SYG? If SYG has been shown to increase the shooting of innocent people then the law needs to be changed, but if there is an increase of violent people are being killed by potential victims (aggressors attacking non aggressors) then SYG is working just like it was designed to work.
Catnlion: This is not what these studies, as an example, are saying:

Jacquelyn C. Campbell et al. (2003) Risk Factors For Femicide in Abusive Relationships: Results From A Multi-Site Case Control Study. Am. J. of Public Health, abstract available at http://www.ajph.org/cgi/content/abstract/93/7/1089:

Access to firearms yields a more than five-fold increase in risk of intimate partner homicide when considering other factors of abuse, according to a recent study, suggesting that abusers who possess guns tend to inflict the most severe abuse on their partners.

Liem, M. , Barber, C., Markwalder, N., Killias, M., Nieuwbeerta, P. (2011) Homicide-suicide and other violent deaths: An international comparison. Forensic Science International. Vol. 207, Issue 1-3, pp. 70-76.

Homicides followed by the suicide of the perpetrator constitute a serious form of interpersonal violence. Until now no study has directly compared homicide-suicides to other violent deaths from multiple countries, allowing for a better understanding of the nature of these violent acts. Using country-specific data, this study describes and compares the incidence and patterns of homicide-suicide as well as the relationship between homicide-suicide, homicide, suicide and domestic homicide in the Netherlands, Switzerland and the United States. The results indicate that cross-nationally, homicide-suicides are more likely than other types of lethal violence to involve a female victim, multiple victims, take place in a residential setting and to be committed by a firearm. Although homicide-suicides display many similarities across the different countries, differences exist regarding age and the use of firearms in the offence. This study indicates that homicides followed by suicides differ from both homicides and suicides in similar ways internationally. Cross-national differences in the availability of firearms may explain the international variation of homicide-suicide rates and patterns.

Harrison: I would have given you an “F” for the lack of understanding this subject. Putting aside that you also don’t understand the language used in research, I find it funny when you use terms like “it could.” Yes, it “could be this” or “it could be that”…
M Todd: Thanks for your comment. Well, the increase in population can play role and could change the estimated and predicted values (I can account for that in what I described above). However, for a sudden “jump” like the one we see after 2005, something changed in the data generating process. At this point, one needs to investigate further why the number of homicides increased by that much. This kind of increase is usually not caused by random variation. I discussed some hypotheses with Mishima666 above.

For me, a death is a death, whether it is a hardcore criminal, a petty thief or an outstanding citizen. A premature death has huge direct and indirect costs on society. If a criminal dies say in a car crash, we would use his or her "preventable" death as part of a cost-benefit analysis for evaluating one or more treatments (for example), mainly because we don’t know (nor are we interested to know) the background of people who die at the scene of a wreck.
Kanuk, since you essentially dodged the entire point of what I said I will assume this means I am correct and your "analysis" is meaningless because if I was wrong you would have pointed out the evidence in your article (and the data) which disproved me.
Harrison: There was nothing to refute, since you’re just stating a misguided opinion. Not once I referred to “missing data.” Unknown factors are not equivalent to missing data, if this is what you’re referring to. This is a way of saying that the increase could be 18% rather than 20%, nothing more than that.
Kanuk, Maybe I misread your data, are you saying all the homicides you sight are involving SYG cases?

If not I not sure I see from your data that a case can be made for a cause and effect for SYG and increase in homicides. My question would be of all the homicides you sight how many of those involved used the SYG as defense? And of those who used SYG for defense how many were found to be unjustified? That would be the real number on which to base any cause and effect pertaining to SYG not just a rise in homicides.

A case could be made that the increase in homicides started at the beginning of the housing crisis. Since 2006 Florida has seen a 49% drop in housing values, high unemployment in construction, and the BP oil spill killed their tourism for two years which was already down because of rising fuel cost. But to say these are the cause of their rise in homicides would be foolish without all the data.
Harrison is a hoot.

The point being the Fla increase in homicides post SYG was not out of line with the national trend. What was out of line was the rise in gun homicides. To correct Kanuk's reasoning, we must apply Harrison's X Factor--how many were criminal acts and how many justifiable.

Perhaps Harrison can explain the difference between a criminally dead person and one killed justifiably. Are the criminally dead stiffer? Deeper blue? More animated?

To be fair, let's apply his missing X Factor to an example. Let's say there were 400 more gun homicides above the trend line, post SYG. Let's split the difference, arriving at 200 criminal and 200 justifiable.
Adding them together, we arrive at the new figure: There were 400 more gun related homicides.

However, that doesn't show any difference and Harrison is a Deep Thinkificator, so we must assume a Harrison X Factor Alternative: 200 justifiably dead people are resurrected, proving there could have been fewer terminal, at least, deaths because they were justifiable, not criminal.

AH! There's the difference!
Now we have the missing meaningless data without which Kanuk's analysis is meaningless.

The rise in gun related homicides might be attributable, to some degree, to the SYG law. There are logical pathways to that conclusion. However, it's a big universe. It might be this, and it might be that. It may simply be The Other Thing.
However, under no circumstance and in no galaxy will it be: Because some were criminal and some weren't.

Looking sideways and squinting, we can apply the Harrison criminal/justifiable question to the abrupt rise in Fla justifiable homicides, which was caused by the SYG law, but that was in the last post.

That's some slick thinkin' thar, Harrison. The Bugtussle Institute of Tecknaulogee must be proud.
Zanuk, What I found with a little research is in Florida SYG has been involved in 11 cases since 2008-11. The results are 5 not charged, 3 pending, and 3 charged but acquitted by the judge. If this is true the actual firearm cases involving all SYG are less than 1/3 of a percent of the total homicides involving firearms. Here is the link to the article in the Tampa Bay Times http://www.tampabay.com/stand-your-ground-law/main.
M Todd (I'll refrain from calling you names): Yet, the same link you gave us provided this (from the same newspaper):

Tally of 'stand your ground' cases rises as legislators rethink law

There are much more than 11 cases. Do you think the legislators are reconsidering the law based on the 11 cases you so proudly told us about?

And this one (again from the same newspaper): Five years since Florida enacted "stand-your-ground" law, justifiable homicides are up

Look carefully at data the bottom of the piece.

I'll come back and comment later, as I have a lot of stuff to do today.
In case you didn't get this:

'Stand your ground' cases

130: The total number of "stand your ground" cases we have identified since the law was passed in 2010*. Of those cases, the number of people who have been cleared of wrongdoing is 74.


*I assume Tampa Bay Times means since 2005.
Furthermore, those are cases above that have been identified by the TBT. Thus, it is very likely that other cases exist and have not been identified by the newspaper.
Ha ha without data there can be no SYG analysis.

Keep your day jobs guys.
Zanuk, As a said that is all I found. Thanks for the additional cases. You sight that there are 130 cases and 74 were cleared that leaves 56 cases. One that means the investigation cleared the 74 because the SYG law did apply leaving 56 shootings that may or may not be justified. Even if all 56 cases are not justified that is still less than 2% of all homicides.

But, the real questions is were any of the 130 cases motivated by the SYG law as the reason for the shooting. The door swings both ways. Before SYG some people may have been hesitant to protect themselves and ended up victims, while others now may be willing to pull the trigger when it could be avoided because of SYG. Even in the 130 cases you sight you would have to go case by case to determine if SYG was the contributing factor as to why they shot instead of not shooting. Then you can make the case for increased homicides as a result of SYG and at that point it would be a matter of public safety to decide if the law benefits or hurts society.
M Todd: I'll get back to you later. I'm not sure whether you're making fun of my penname, but is Kanuk. This is why I indicated that won't call you names above.
"But, the real questions is were any of the 130 cases motivated by the SYG law as the reason for the shooting."

Exactly.

The answer? Nobody knows.
Kanuk wow sorry did not mean to add a Z. Not making fun, or trying to be sarcastic just a lousy typist. I find the discussion very informative and without malice from you or anyone else. Again sorry for the Z will make sure to watch my typos.
Harrison,
That question was never presented as having a certain answer. However, when a significant event is followed by a significant result, it greatly increases the probability of a degree of significant relationship. The most likely proximate causes are considerations drawn from logical relationships. A guide to further study and, though not conclusive, they still carry weight.

As far as the 130 issue goes, MT and Harri, the question isn't simply how many were justified under SYG. MT is declaring the cases cleared because of SYG as justifiable and the rest questionable.
The problem with that is the issue is that SYG changed the identity of what was considered justifiable, so it can't be used to define the 74 as unquestionable within the larger parameter of before/after.
Logically (I'm no statistician), the question is how many of the 74 were justifiable under the old law. It's obvious that none of the 56 were. So, MT, the reverse is true -- it's the 74 that are questionable.

When debating the issue of whether the SYG law prompted the increase in gun homicides, it's a question of probabilities. In that, empiricism tends to be stronger than the probability there is another or a combination of other influences unknown. It doesn't make the inferences drawn from evidence right, just more likely to be right.

To effectively rebut the strong correlation inference, you need something better than the simple declaration that it isn't proven. You need to offer something tied to an event or trend beyond stream-of-conscience meandering. If the housing bust, etc, then define a logical path to the connection.
Because the SYG event and homicide numbers are concrete and directly related in self-defense-guns, not the indirect housing-self defense-guns, the correlation/possible causation case is stronger than yours. Though it is only offered as increased probability, you need some other event that couldn't be and hasn't already been dismissed as statistical noise--the proposed influences that, especially in their ethereal form, are logically reduced to being far less likely influential enough to be significant.

Because each questionable case cannot be parsed to a legal opinion of what was justifiable before or after the SYG law, that number may never be known. What can be logically assumed, however, is fewer of those cases would have been justifiable under the old law. If not, then the law we know was changed was written for no reason, as it didn't change anything. It was changed, so there is a difference.

As far as that difference being insignificant to the point the law doesn't need to be changed again, it seems a cruel and absurdly unnecessary defense for a new law that didn't actually enhance anyone's right to self defense. Under Duty To Retreat, you always had the right to deadly force if there was no way out. If the attack was sudden, the deadly force could be as sudden, and justified.
Where SYG makes a difference is it can embolden people to escalate conflicts that could be diffused, inviting whatever may invoke the loose standard of the SYG defense. As an unconsidered and therefore tangential influence on what a perp thought was a criminal act, it can be used to free people who acted with malicious intent.

The law wasn't needed and too often excuses murder or manslaughter, encourages escalating conflicts among those who know of it's lax requirements, and even frees people who were certain they had performed a criminal act--and under the old law, did.

I'm not seeing any upside here, guys. Why, then, the SYG law?
When one titles an article "Added Homicides: More evidence against “Stand Your Ground”?" the article itself should present evidence regarding said topic.

An example of false causality (which you employed though didn't present as such) would be this:

"We were robbed right after that family moved in, so they must be the culprits."

What I have against your article is how hard you try to make everything appear logical and scientific so that, naturally, the results aren't the result of wishful thinking but, instead, a mathematical certainty.

As I said, crime could be worse because the Florida economy is worse. Or, as someone else said, SYG could give possible crime victims the confidence they need to defend themselves. Or SYG could be causing mass murder in the streets.

Nobody knows and all the wishful thinking on your part won't change that fact.

Now if you want to ask why, in a subjective way, SYG became law and why it might be beneficial or not, that's a different subject.
Paul: Thank you the great comments. Couldn’t agree more. I’ll add a few things below.

M. Todd: Thanks for the explanation. Paul provided excellent comments on this topic, but I’ll add a few more points:

First, it is important to point out that the purpose for this kind of study is to determine whether the number of murders has increased beyond what we would expect if the law would not have been enacted (please see my first post, which describes how this kind of studies works). We know when the law was introduced and it is anticipated that it will have an effect on the number of homicides. The hypothesis that this kind of law has absolutely no effects is non-sense. This is in the same line as saying that if we increase the speed limits from 55 mph to 70 mph, we won’t see an increase in motor vehicle crashes. You don’t even need to conduct sophisticated analyses to dispute this statement. Looking at the raw data will tell you everything you need to know. Harrison will tell us that other factors are at play, but we’ll leave that aside.

Once we see a trend that confirms our hypothesis, then we can go deeper and conduct a detailed analysis aiming at understanding why we have seen such increase. So far, we have seen a lot of anecdotal evidences that all pretty much say the same thing in Florida and elsewhere. In this regards, I used the data that were available to everybody. If I had more time and resources (i.e., research funds to cover my time), I would have spent more time to get even more accurate results. However, for a blog post, this is more than enough.

Second, as I mentioned above (Paul referred to it as well), we should not only focus on these 130 cases that were identified by the TBT. They have limited resources and it’s possible that they just took a sample given the time and money they can spend on this subject. More than likely, there are additional cases out there. Another important point is that we don’t know how many people out there have killed somebody (knowing that they may not be prosecuted), but were told by their legal counsel not bother claiming self-defense because it will be waste of money and effort. Those will never be part of the tally, hence the importance of looking at the totality of the homicides, subsequently focused on different subsets.

Third, as Paul indicated, the question is not how many homicides fall under the SYG, but whether or not more people have been killed and should not have been, if such a law was not introduced. At this point, the raw number is no longer relevant (whether it is 10, 20, 200, or 2,000 additional deaths*). If this is the case, the law has failed. As I indicated above, a premature death is a premature death and the person’s criminal history is irrelevant. I suggest that you read the interview documented in the TBT in the link above about Billy Kuch was very drunk and tried to enter the wrong house. He was shot, not in the house, but on the lawn with his hands up. Fortunately, he survived, but probably with lifelong consequences.

*We should also include people who were shot, stab, etc., but survived, such as Billy Kuch.
...about Billy Kuch who was very drunk and tried to enter the wrong house.
Kanuk, sometimes the cause and effect are not so clear cut. For example you sight the change in traffic speeds. We went from 70 to 55 and the death rate dropped. But, reducing the speed limit was not the only factor that dropped highway deaths in the summer 1974. What also needed to be factored in was the rising cost of fuel cut driving across the board. People started car pooling which reduced the number of cars on the road. And there was a shift from driving on rural two lane roads to the interstate system that was expanded in the 70s. And we started to take drinking and driving seriously. Yes, the 55 an hour law helped, but as the price and supply of gas stabilized traffic fatalities rose again.

The point is I will agree with you that in some of the cases SYG will be a factor and reason for some of the increase of homicides. Maybe a study comparing unjustified deaths vs. saved innocent life as a result of the law. If the unjustified deaths out way the innocent lives saved then the law is not a benefit and should either be changed or revoked.
M. Todd: Yes, I agree that other factors, such as the ones you noted, have also affected the reduction observed when the speed limit was lowered during the oil crisis in the early seventies. A few years afterwards, scientists and researchers started looking at the data and noticed the significant drop in motor vehicle crashes (especially the fatal ones), an unexpected result at the time. This explained why the speed limit was maintained for a very long time after the crisis was over. Because of this drop, further research was done to examine why this happened and remove the effects of these other factors. Here’s a sample of work done on this topic:

Richards, D., Cuerden, R. (2009) The Relationship between Speed and Car Driver Injury Severity. Road Safety Web Publication 9. Department for Transport. London, U.K.

Elvik, R., Christensen, P., Amundsen, A. (2004) Speed and Road Accidents. An Evaluation of the Power Model. Report 740/2004, Institute of Transport Economics, Oslo, Norway.
Report here

Taylor, M.C., Lynam, D.A., Baruya, A. (2000) The effects of drivers' speed on the frequency of road accidents. TRL Report, 421. Transport Research Laboratory, Crowthorne, U.K.

Thanks for the discussion. Up early?
Kanuk, SYG does not reduce crime. And knowing human nature there will be some who will shoot first thinking the law justifies their actions. There are just some people out there who are violent sociopaths who think nothing of killing other people regardless of any law.

From what I understand about the law it was designed to prevent automatic prosecution of those in real and honest cases of self defense. SYG is not a catch all and it is not perfect. SYG is just another symptom of our nations growing fear of the future, society, and each other in general.

Your timeline also pretty much matches the housing crash and downward spiral of the economy, rising unemployment rates, our growing mistrust of the government to solve our problems, and the slide of the middle class into poverty. I would have to say these factors are more universal and contribute to the rise in homicides than SYG. Removing SYG will not impact the over all rise in homicides, it will just place the burden of self defense unfairly back on the individual not the governmental judicial system.
M Todd writes: Your timeline also pretty much matches the housing crash and downward spiral of the economy, rising unemployment rates, our growing mistrust of the government to solve our problems, and the slide of the middle class into poverty.

I’m sure you can explain this:

Change in homicides: +28.1%
Change in violent crimes: +2.9%

Looking at this Housing crisis by location, we get this for the exact time period:

California
Change in homicides: -0.7% (~2,500 homicides per year)
Change in violent crimes: +2.9%

Arizona
Change in homicides: +4.5% (~450 homicides per year)
Change in violent crimes: -0.7%

Nevada
Change in homicides: +8.7% (~200 homicides per year)
Change in violent crimes: -0.4%

You might want to check these ones too (the two most important cities affected by the housing bubble in the USA):

Miami Crime Rate Report (Florida)

Tampa Crime Rate Report (Florida)

No spikes can be seen in 2006-2007. In short, we can put to rest that the housing bubble caused the 28% increase in murders.
The links did not work (?). I put the original ones here again:

http://en.wikipedia.org/wiki/United_States_housing_bubble#Extent

http://www.cityrating.com/crime-statistics/florida/miami.html

http://www.cityrating.com/crime-statistics/florida/tampa.html
Kanuk, Maybe you are right and the housing crisis as a factor has no effect on Florida's homicide increase. It is also interesting that two out of the three states you mentioned are SYG states and some of the most liberal gun laws in the country. So maybe Florida is just a violent state that needs laws like SYG to protect the law abiding and peaceful citizens.
M Todd: I'm not sure about that. The only state that has not enacted a SYG law recently (Nevada was last year - too early to tell; Arizona in 2006) is the one that experienced a decrease among the three states listed above. In fact, this state has experienced a constant decrease since 2005 (even when we account for changes in the number of people living in the state).
It’s good to see that another study, using a different approach, supports the analyses presented above:

Study: ‘Stand your ground’ laws result in an additional 4 to 7 killings per month