# Why has crime declined so much over the past 20 years? **URL:** \ **Category:** Great Debates\ **Created:** [May 15, 2014, 1:52am UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492 "2014-05-15T01:52:44Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Chihuahua](https://avatars.discourse-cdn.com/v4/letter/c/dec6dc/32.png) [@Chihuahua](https://boards.straightdope.com/u/Chihuahua)\ **Post date:** [May 15, 2014, 2:56pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/21 "2014-05-15T14:56:09Z")
> [@Bricker](#): > > I hate to ask for a link – but is this just a correlation? > > Or was there some reasoning to suggest causation? > > [Because living in a poor country increases penis size, a pirate shortage caused global warming, and ice cream consumption leads to murder.](http://www.buzzfeed.com/kjh2110/the-10-most-bizarre-correlations) I believe the hypothesis that Internet Explorer incites murders deserves further research. ---
**Author:** ![Simplicio](https://avatars.discourse-cdn.com/v4/letter/s/c37758/32.png) [@Simplicio](https://boards.straightdope.com/u/Simplicio)\ **Post date:** [May 15, 2014, 2:56pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/22 "2014-05-15T14:56:46Z")
> [@Fuzzy\_wuzzy](#): > > Your point about the reasons for crime rate decline still being debated today are interesting. Again, dont underestimate vested interest here. Many social scientists/workers and criminologists have a vested interest in it not being a birth rate linked model. Or of at least minimizing such an explanation. Eh, that’s kind of my point. The demographic explanation is simple enough that you don’t really need to be sociologist to do a back of the envelope check to see if its plausible. From the earlier thread: > [@Simplicio](#): > > The absolute number of 20-25 year olds has barely changed at all since 1980 (they’re a smaller chunk of the population, but not a smaller group in absolute terms). The absolute number of homicides has dropped by more then a third in the same period. It isn’t just that young people make up a smaller proportion of the population, young people are also committing fewer crimes. ---
**Author:** ![SciFiSam](https://avatars.discourse-cdn.com/v4/letter/s/47e85d/32.png) [@SciFiSam](https://boards.straightdope.com/u/SciFiSam)\ **Post date:** [May 15, 2014, 3:00pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/23 "2014-05-15T15:00:23Z")
A lower rate of infant mortality. I couldn’t find a good cite to back that up, though. Your kids are more likely to live = you spend more time teaching your kid, or paying other people to = they have less time to get up mischief and have more to lose if they do. Rich kids commiting crimes will lose little compared to the population at large, but they will lose a lot among their peer group. Doesn’t always work out, obviously, but on the whole it seems to. ---
**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\ **Post date:** [May 15, 2014, 3:13pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/24 "2014-05-15T15:13:29Z")
> [@XT](#): > > A case has been made several times on this board (and fairly convincingly as well) that regulations limiting or banning the use of lead has had a measurable effect on this. While I don’t think it’s completely proved, I’d say the evidence is compelling, and better than anything else I’ve seen. If it is true – damn! How many lives, victims’ and criminals’ alike, were needlessly ruined just so that car engines would not knock! ☹ ---
**Author:** ![Farin](https://avatars.discourse-cdn.com/v4/letter/f/e79b87/32.png) [@Farin](https://boards.straightdope.com/u/Farin)\ **Post date:** [May 15, 2014, 4:56pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/25 "2014-05-15T16:56:31Z")
> [@Simplicio](#): > > “Correlation doesn’t prove causation” was originally a useful warning against ignoring the possibility of confounding variables. But its become a sort of anti-science buzz word, a lazy way to handwave away any study. A strong correlation does in fact, prove two things are casually linked, either directly to each other or each to a third variable. The warning was against looking at two variables, assuming a relationship, and then acting on it. This warning is still very, very valid. For instance, [US spending on science, space, and technology correlates with suicides by hanging, strangulation and suffocation](http://www.tylervigen.com/view_correlation?id=1597)? We, as a country need to stop funding science, NASA and technology! We are killing our citizens! Or how about [Divorce rates in Maine correlating with per capita consumption of margarine in the US](http://www.tylervigen.com/view_correlation?id=1703)? We should all stop eating butter replacements so that our citizens in Maine will stay together forever! We also need to [stop skiing facilities from generating revenue because it’s killing people with their bed sheets](http://www.tylervigen.com/view_correlation?id=1864)! The humanity! I’m only poking fun, but there are many unrelated things that correlate strongly and the correlation is illusory. 😃 ---
**Author:** ![Bricker](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@Bricker](https://boards.straightdope.com/u/Bricker)\ **Post date:** [May 15, 2014, 5:21pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/26 "2014-05-15T17:21:12Z")
> [@BrainGlutton](#): > > If it is true – damn! How many lives, victims’ and criminals’ alike, were needlessly ruined just so that car engines would not knock! ☹ Cosmos devoted an episode to this recently, detailing how the realization about lead in the atmosphere arose from Clair Patterson’s use of lead isotopic data to determine the age of the Earth. Patterson tried to get “clean” samples and was amazed to discover how much lead was in the environment – but only from the short term; samples taken from even a hundred years ago showed dramatically less lead. In defense of the inventors of tetraethyllead additives, they simply had no idea they were pumping such quantities of poison into the world. ---
**Author:** ![casdave](https://avatars.discourse-cdn.com/v4/letter/c/c6cbf5/32.png) [@casdave](https://boards.straightdope.com/u/casdave)\ **Post date:** [May 16, 2014, 9:20am UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/27 "2014-05-16T09:20:01Z")
I would like to see data that sows the crime rates prior to the introduction of lead in fuel. Also there should be some sort of link between the amounts of lead in the air and crime. Lead will also stay in the environment for some time, lead was also used in paints and other products. I think that lead did enable lots of crime, but not in an obvious way. Lead in fuel means that cars are being used, and that means increased mobility, the fact is that cars are widely used in crime, either directly or indirectly. ---
**Author:** ![Simplicio](https://avatars.discourse-cdn.com/v4/letter/s/c37758/32.png) [@Simplicio](https://boards.straightdope.com/u/Simplicio)\ **Post date:** [May 16, 2014, 9:31am UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/28 "2014-05-16T09:31:53Z")
> [@Farin](#): > > I’m only poking fun, but there are many unrelated things that correlate strongly and the correlation is illusory. 😃 Those things don’t really correlate strongly. A strong correlation is one that is unlikely to happen by chance. If a correlation is strong, it meets a high enough threshold that its unlikely to be due to statistical noise or happanstance. The graphs you show were created by going through thousands of data-sets to find graphs that had a one-and-a-thousand chance of happening. But if you do that, you obviously need to readjust your threshold for what counts as “strong” to something much less likey to occur then a one-in-a-thousand chance. If things correlate strongly, then they are by definition not due to chance. They’re either directly causal or causally linked to some other variable. ---
**Author:** ![Locrian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/locrian/32/14146_2.png) [@Locrian](https://boards.straightdope.com/u/Locrian)\ **Post date:** [May 16, 2014, 10:08am UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/29 "2014-05-16T10:08:56Z")
> [@TriPolar](#): > > It’s all of the above. The world is a complicated place, no single factor caused the rate of violent crime to rise in the first place, no single factor caused it’s decline. The only thing you can count on is that someone claiming there was a single dominant cause for the increase or the decrease is wrong. This! This is what I say a lot during philosophical (well, in a bar) discussions. One answer is never the answer, and I think it’s a human fallacy that we all want just ONE answer to our particular problem. IOW, maybe all of the examples so many have already posted concerning a reduction in crime are true in all civilized societies, just in different amounts. I think the decrease must be a blend of so many improvements in society, science, technology, media, etc., that affect any culture with a reduction with violent crime. Hey, maybe all the lead removed in some American suburb reduced crime there, but maybe an increase in media and communication technology reduced it in another part of the blue marble. Add in some anti-depressant tablets and legalized marijuana might be contributing along with new colors on the city’s buses and a free donut day at the local bakery. Seeing shows on basic cable showing someone how prison life really is and how a simple text message is what got the perp caught might be giving some influence to those that may commit crime. > [@](#): > > \*\*Simplico:\*\*I disagree. Individual crimes are obviously complicated things with many causes. But the big increase, and then drop, in crime in the late 20th century was such a wide-spread phenomenon, was so similar across such a wide swath of countries and smaller geographic regions and was so large, that I think its unlikely to have been due to some large number of smaller factors. To the first order, anyways, **a single cause seems far more probable**." Nope, can’t see this. You state it was a wide-spread phenomenon and spread across a wide number of countries. If we were talking about four adjacent neighborhoods in Punxsutawney, PA, I’d say you have a point. But considering the differences in culture, air, climate, temperature, disease, distance, etc., I have to go with many causes. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [May 16, 2014, 10:16am UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/30 "2014-05-16T10:16:56Z")
It’s all the fault of the man who may be the cause of more premature deaths than any other - Thomas Midgley Jr. He was the man who put lead in gasoline. He discovered that tetraethyl lead (TEL) stops knock in internal combustion engines while working for Charles Kettering and General Motors in 1921. All of them knew that lead was toxic. He was also invented Freon, a chlorofluorocarbon (CFC), which would result in the thinning of the stratospheric ozone layer over Antarctica and the Arctic years later. In **December 1922** the US Surgeon General, H.S. Cumming, wrote: “Inasmuch as it is understood that when employed in gasoline engines, this substance will add a finely divided and nondiffusible form of lead to exhaust gases, and furthermore, since lead poisoning in human beings is of the cumulative type resulting frequently from the daily intake of minute quantities, it seems pertinent to inquire whether there might not be a decided health hazard associated with the extensive use of lead tetraethyl in engines.” cf [Three Inventions of Thomas Midgley Jr, the First Geoengineer](http://www.dailykos.com/story/2010/01/26/830326/-Three-Inventions-of-Thomas-Midgley-Jr-the-First-Geoengineer) ---
**Author:** ![brickbacon](https://avatars.discourse-cdn.com/v4/letter/b/898d66/32.png) [@brickbacon](https://boards.straightdope.com/u/brickbacon)\ **Post date:** [May 16, 2014, 2:05pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/31 "2014-05-16T14:05:52Z")
> [@Locrian](#): > > This! This is what I say a lot during philosophical (well, in a bar) discussions. One answer is never the answer, and I think it’s a human fallacy that we all want just ONE answer to our particular problem. This thinking is just as facile as what you accuse other people of. Plenty of things have one answer or primary cause. > [@Locrian](#): > > I think the decrease must be a blend of so many improvements in society, science, technology, media, etc., that affect any culture with a reduction with violent crime. Hey, maybe all the lead removed in some American suburb reduced crime there, but maybe an increase in media and communication technology reduced it in another part of the blue marble. You can correct for most of those things. > [@Locrian](#): > > Nope, can’t see this. You state it was a wide-spread phenomenon and spread across a wide number of countries. If we were talking about four adjacent neighborhoods in Punxsutawney, PA, I’d say you have a point. But considering the differences in culture, air, climate, temperature, disease, distance, etc., I have to go with many causes. The problem with your theory is that it is less likely than one cause that fits the data. The issue not just that we saw a drop all over the place, but that the drop happened as lead was phased out in different places at different times. The idea that multiple, different factors happened to produce this change, and that these factors also happen to all correlate to lead use is highly unlikely. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [May 16, 2014, 2:13pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/32 "2014-05-16T14:13:31Z")
> [@Simplicio](#): > > Obviously lead isn’t the sole cause of crime. If we had zero lead, there would still be crime, and other factors would cause it to go up and down. But I think the case is very strong that lead is the sole cause of the crime wave that took place in the last half of the 20th century. > It isn’t just that young people make up a smaller proportion of the population, young people are also committing fewer crimes. Your own statements are inconsistent with the point you try to make, and admit that there is not a sole cause. Which is quite reasonable because there isn’t any sole cause. Politics is full of simplistic concepts, change this one little thing and everything gets better. Unfortunately the world is a more complex place. ---
**Author:** ![Simplicio](https://avatars.discourse-cdn.com/v4/letter/s/c37758/32.png) [@Simplicio](https://boards.straightdope.com/u/Simplicio)\ **Post date:** [May 16, 2014, 2:20pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/33 "2014-05-16T14:20:58Z")
> [@TriPolar](#): > > Your own statements are inconsistent with the point you try to make, and admit that there is not a sole cause. I said there is no sole cause to crime in general. But there is a sole cause to the general decline in crime over the last twenty years, which was the OP’s question. Those statements aren’t inconsistent. ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [May 16, 2014, 2:23pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/34 "2014-05-16T14:23:01Z")
> [@casdave](#): > > I think that lead did enable lots of crime, but not in an obvious way. Lead in fuel means that cars are being used, and that means increased mobility, the fact is that cars are widely used in crime, either directly or indirectly. 😕 Huh? Are you suggesting that rates of car use and increased mobility are **lower** now than they were during the crime wave under discussion? Because they certainly aren’t. If increased car use led to increased crime, we in the US should currently all be living in Cape-Town-level situations of criminal excess. If you’re going to stick by this hypothesis, you’re going to have to explain why you think increased car use in the 1960’s enabled a crime wave but the much higher increase in car use of the past few decades has coincided with a significant **drop** in crime. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 16, 2014, 2:44pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/35 "2014-05-16T14:44:07Z")
> [@](#): > > Quoth **Simplicio** : > > Most of those things aren’t correlations. A correlation is a mathematical relationship between two quantities, not just a vague “one thing goes up as another thing goes up”. Actually, “one thing goes up as another thing goes up” is a mathematical relationship, and needn’t be at all vague. It is, in fact, the mathematical relationship that bears the name “correlation”. That’s exactly what a correlation is. It sounds like what you’re referring to is goodness of fit of a model to data. But while this is often used as a proxy for correlation, it is not the same thing. For instance, if my data consists of the X-Y pairs (0,5), (3,4), (4,3), (5,0), (4,-3), (3,-4), (0,-5), (-3,-4), (-4,-3), (-5,0), (-4,3), (-3,4), then in my data, X and Y have no correlation whatsoever, but they can be fit extremely well to the model X^2 + Y^2 = 25. ---
**Author:** ![theR](https://avatars.discourse-cdn.com/v4/letter/t/977dab/32.png) [@theR](https://boards.straightdope.com/u/theR)\ **Post date:** [May 16, 2014, 3:01pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/36 "2014-05-16T15:01:54Z")
> [@casdave](#): > > I would like to see data that sows the crime rates prior to the introduction of lead in fuel. Then click on the link to the other thread about lead. To be fair, that thread has a link to an even older thread from 2012 that has many more links to actual news articles and published studies on the subject. [Is the recent drop in violent crime due to banning lead in gasoline?](http://boards.straightdope.com/sdmb/showthread.php?t=673972) I guess we should be resigned to having another lead thread, but really at this point maybe this one should just be merged with one of the older threads so all the information is in one place. ---
**Author:** ![nevadaexile](https://avatars.discourse-cdn.com/v4/letter/n/eb8c5e/32.png) [@nevadaexile](https://boards.straightdope.com/u/nevadaexile)\ **Post date:** [May 16, 2014, 3:36pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/37 "2014-05-16T15:36:21Z")
I would advise that the OP go down to his or her local police station and see how many outstanding crimes that their police force has and then ask if crime is really decreasing or if the authorities are manipulating data to make it appear that crime is decreasing. As far as I know in the Midwestern city that I live near: [ol] [li]You can go out at any hour of the day or night and buy drugs of all varieties and quantities. There’s also booming trades in meth and illegal prescription medicines.[/li][li]Stolen vehicles are routinely found either burned out or parked in long-term lots.[/li][li]There’s no decrease in home or vehicle burglaries.[/li][li]Last year, there were a record number of homicides for the entire county.[/li][li]A quick perusal of Craigslist shows me that I can buy “new in box” laptops, baby formula, Tide detergent,hair products and other items which have obviously been obtained from either shoplifting or employee theft.[/li][li]The trade in scrap metal is booming as as is the theft metal For scrap.[/li][li]White collar frauds,especially identity theft and Medicare frauds are on the increase[/li][/ol] I see that the DOJ is reporting that fewer crimes are being committed. However, that appears to indicate that fewer crimes are being _ **reported** _ more than it does that there is a decrease in crime. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [May 16, 2014, 3:42pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/38 "2014-05-16T15:42:31Z")
> [@Bricker](#): > > In defense of the inventors of tetraethyllead additives, they simply had no idea they were pumping such quantities of poison into the world. Thomas Midgeley knew exactly what he was doing; he actively covered up numerous reports of mass sickness caused by lead exposure at Ethyl Gasoline Corporation facilities. ---
**Author:** ![Evil\_Captor](https://avatars.discourse-cdn.com/v4/letter/e/f17d59/32.png) [@Evil\_Captor](https://boards.straightdope.com/u/Evil_Captor)\ **Post date:** [May 16, 2014, 3:53pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/39 "2014-05-16T15:53:00Z")
> [@theR](#): > > Then click on the link to the other thread about lead. To be fair, that thread has a link to an even older thread from 2012 that has many more links to actual news articles and published studies on the subject. > [Is the recent drop in violent crime due to banning lead in gasoline?](http://boards.straightdope.com/sdmb/showthread.php?t=673972) > > I guess we should be resigned to having another lead thread, but really at this point maybe this one should just be merged with one of the older threads so all the information is in one place. No, just let the links to the lead threads do the ignorance fighting. Clearly, some people, for whatever reason, don’t want to see that link. I have no idea why not, but they don’t. (See post 37.) If they won’t be persuaded by the numbers, they won’t be persuaded at all. It’s not worth the trouble. ---
**Author:** ![CarnalK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnalk/32/486_2.png) [@CarnalK](https://boards.straightdope.com/u/CarnalK)\ **Post date:** [May 16, 2014, 4:04pm UTC](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492/40 "2014-05-16T16:04:49Z")
> [@nevadaexile](#): > > I would advise that the OP go down to his or her local police station and see how many outstanding crimes that their police force has and then ask if crime is really decreasing or if the authorities are manipulating data to make it appear that crime is decreasing. > > As far as I know in the Midwestern city that I live near: > > [ol] > [li]You can go out at any hour of the day or night and buy drugs of all varieties and quantities. There’s also booming trades in meth and illegal prescription medicines.[/li][li]Stolen vehicles are routinely found either burned out or parked in long-term lots.[/li][li]There’s no decrease in home or vehicle burglaries.[/li][li]Last year, there were a record number of homicides for the entire county.[/li][li]A quick perusal of Craigslist shows me that I can buy “new in box” laptops, baby formula, Tide detergent,hair products and other items which have obviously been obtained from either shoplifting or employee theft.[/li][li]The trade in scrap metal is booming as as is the theft metal For scrap.[/li][li]White collar frauds,especially identity theft and Medicare frauds are on the increase[/li][/ol] > > I see that the DOJ is reporting that fewer crimes are being committed. However, that appears to indicate that fewer crimes are being _ **reported** _ more than it does that there is a decrease in crime. People keep ignoring that these increases and decreases in violent crime occur across nations. So you are contending that there was fudging by authorities in all countries to increase crime then they all decided to fudge numbers to show a decrease in crime. And Farin’s earlier “-We incarcerate so many people that we keep the criminals behind bars instead of on the streets.” is very obviously American-centric. The lead theory seems to explain crime rates in multiple jurisdictions that have a wide variety of justice and political systems. [Previous page](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492.md?page=1) [Next page](https://boards.straightdope.com/t/why-has-crime-declined-so-much-over-the-past-20-years/688492.md?page=3)