Since it's never explained what this is about, before you read the article you might want to know:<p>> The lead–crime hypothesis is the association between elevated blood lead levels in children and increased rates of crime, delinquency, and recidivism later in life. (Wikipedia)<p>(I was interpreting "lead" as related to leadership or being (mis)lead, and was thoroughly confused for the first few paragraphs until I decided to just look it up myself.)
Some previous lead-crime threads:<p><i>An Updated Lead-Crime Roundup (2018)</i> - <a href="https://news.ycombinator.com/item?id=20101446" rel="nofollow">https://news.ycombinator.com/item?id=20101446</a> - June 2019 (11 comments)<p><i>New Evidence That Lead Exposure Increases Crime (2017)</i> - <a href="https://news.ycombinator.com/item?id=17888291" rel="nofollow">https://news.ycombinator.com/item?id=17888291</a> - Aug 2018 (147 comments)<p><i>Lead: America's Real Criminal Element (2013)</i> - <a href="https://news.ycombinator.com/item?id=17350912" rel="nofollow">https://news.ycombinator.com/item?id=17350912</a> - June 2018 (141 comments)<p><i>A Basic Cohort Test of the Lead-Crime Hypothesis</i> - <a href="https://news.ycombinator.com/item?id=16349365" rel="nofollow">https://news.ycombinator.com/item?id=16349365</a> - Feb 2018 (45 comments)<p><i>New Zealand Study Provides More Support for Lead-Crime Hypothesis</i> - <a href="https://news.ycombinator.com/item?id=16023218" rel="nofollow">https://news.ycombinator.com/item?id=16023218</a> - Dec 2017 (36 comments)<p><i>A Study That Bolsters the Lead-Crime Hypothesis</i> - <a href="https://news.ycombinator.com/item?id=14488520" rel="nofollow">https://news.ycombinator.com/item?id=14488520</a> - June 2017 (121 comments)<p><i>Lead Water Pipes in 1900 Caused Higher Crime Rates in 1920?</i> - <a href="https://news.ycombinator.com/item?id=11625158" rel="nofollow">https://news.ycombinator.com/item?id=11625158</a> - May 2016 (67 comments)<p><i>Lead and Crime: Another Look</i> - <a href="https://news.ycombinator.com/item?id=10868980" rel="nofollow">https://news.ycombinator.com/item?id=10868980</a> - Jan 2016 (11 comments)<p><i>Did removing lead from petrol spark a decline in crime?</i> - <a href="https://news.ycombinator.com/item?id=7618871" rel="nofollow">https://news.ycombinator.com/item?id=7618871</a> - April 2014 (270 comments)<p><i>Leaded gasoline caused violent crime? Critiques wanted.</i> - <a href="https://news.ycombinator.com/item?id=5017804" rel="nofollow">https://news.ycombinator.com/item?id=5017804</a> - Jan 2013 (1 comment)<p><i>America's Real Criminal Element: Lead</i> - <a href="https://news.ycombinator.com/item?id=5002806" rel="nofollow">https://news.ycombinator.com/item?id=5002806</a> - Jan 2013 (4 comments)<p><i>The Crime of Lead Exposure </i> - <a href="https://news.ycombinator.com/item?id=2609158" rel="nofollow">https://news.ycombinator.com/item?id=2609158</a> - June 2011 (3 comments)<p><i>Has use of lead-free gas decreased the crime rate?</i> - <a href="https://news.ycombinator.com/item?id=71878" rel="nofollow">https://news.ycombinator.com/item?id=71878</a> - Oct 2007 (4 comments)
The lead-crime hypothesis is almost certainly true but the mass media reaction to it just shows how much is wrong with our society.<p>First of all, the lead-crime hypothesis is good news. It is great to realize that small entirely achievable environmental changes can cause such marked improvement in wellbeing in people's lives.<p>But for some reason it has not been accepted as good news by the mass media. And then you have papers like the one discussed by the article that try to debunk the theory on absolutely ridiculous grounds. (You see there are no studies disproving this theory therefore there must be studies disproving this theory, therefore this theory is wrong. What a bunch of BS!)<p>So why is the lead crime hypothesis treated so negatively by our elites? Perhaps to avoid another round of massive litigation. Perhaps to prevent people from finding other ways other pollution can affect people's behavior and thus prevent the banning of other substances and other rounds of massive litigation. Or perhaps to preserve an image key in international culture -- the violent city youth.
> I don't get this. If, say, the actual effect of lead on crime is 0.33 on their scale (a "large" effect size) then you'd expect to find papers clustered around that value<p>You'd expect them to be clustered around that value symmetrically, right? That's clearly not the case in the diagram that the blog post author quoted. There's a cluster around very weak positive effects, and then a long tail of strong positive effects but no matching long tail of weak negative ones. This suggests either that the negative results were truncated out, negative results have been hacked to positive ones, or there is some confounding factor at play. And I think the modeling in the paper is just an attempt at finding the confounding factor, and not finding one.<p>That said, the author's arguments around negative results being publishable in this field + studies not disappearing seem pretty strong.<p>(Or, at least this is my reading of the situation as a total amateur.)
I don’t know much about stats, but the idea that a theory is bunk because no studies have shown it’s bunk is pretty absurd. How many studies fail to show an association between narcotics abuse and crime? Zero? Then it must be fake?
> This means that 22 out of 24 studies found positive associations.<p>> The authors present a model that says there should be more papers showing negative effects just by chance.<p>To the layperson it sure looks like the lead-crime hypothesis is confirmed. Really curious to see a more in-depth follow-up on this meta-analysis.
Well, we're not "post-lead" anyway. Particularly in larger, older cities there is a lot of lead paint around, and this tends to be clustered in older, poorer neighborhoods with unrenovated and more poorly maintained dwellings. I'm not sure this is a good meta analysis.
> In fact, because the sample size for homicides is so small, exactly the opposite is true. In general, studies that look at homicide rates in the '80s and '90s simply don't have the power to be meaningful. The unit of study should always be an index value for violent crime and it should always be over a significant period of time.<p>Homicide rates are used for good reasons: they are least subject to reporting variations, they are hardest to fudge, and it’s the most serious crime.<p>Some evidence against the lead-crime hypothesis is the recent (2020-2021) jump in homicides in the U.S.
I think it's understandable why the lead-crime hypothesis was/is so popular, because it it's an alternative to the hypothesis that increased incarceration and abortion reduced crime, which, politically, are less popular. It's more politically correct to blame lead poisoning than insufficient policing.
Though I think I get the argument, it seems quite absurd that we now have arrived at "The absence of evidence of absence is evidence of absence."
It's astonishing to me that any large scale population study can ever prove anything, given how incredibly complex and unique peoples' lives are, and how many confounding factors may play a part at some point in those lives over many years.
It's insane that publication bias is still a thing that has to be considered in a meta-analysis, that you can't just find any study on a topic ever made.
Isn't this more of a critique of meta-analysis itself? It seems pretty suspect to take a collection of <i>published</i> studies with different populations and different criteria and derive any meaningful meta product from them, especially since we know most research is never actually published.
Lead poisoning = lower IQ & educational attainment<p>poor education & lower IQ = locked out of the labor force and more likely to make bad decisions in life<p>not rocket science.
Freakonomics re-visit the abortion crime link and also talk about lead in 2019 - <a href="https://freakonomics.com/podcast/abortion/" rel="nofollow">https://freakonomics.com/podcast/abortion/</a><p>The abortion model is simple. Unwanted babies to mothers who don't want them will not grow up well.<p>We know lots of things target IQ, but the lead model is really complex, it hypothetically reduces impulse control across the entire population and with really tiny amounts in the environment.<p>When I see it proven in mice not humans I'll be more convinced. (And not large amount of lead in their water bowl)