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Why half of all drowners are black: physical proof

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ApostateAbe

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I used a less provocative title for this same thread posted in other forums, but it has still resulted in a deleting and banning streak. That's because black lives matter but not as much as dogma.

American blacks are many times more likely to drown than whites (http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6319a2.htm#tab), fulfilling the crude racial stereotype that "blacks can't swim." It could be just a cultural difference (fewer blacks have learned to swim therefore more drowning), but the physical data seems to have predictive power: blacks are more likely to drown due to different body densities. I will lay out the data and the math. Check the math, if you are so kind. I don't claim the math is infallible.

The study "Prediction of Body Density from Skinfolds in Black and White Young Men," (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1470565/) published in Human Biology in 1988, found that young white men have an average body density 1.065 g/mL, with a standard deviation of 0.012 g/mL, and young black men have an average body density of 1.075 g/ml, with a standard deviation of 0.015 g/mL. The difference in body densities may follow from a difference in bone density (http://ajcn.nutrition.org/content/71/6/1392.long), a difference in muscle mass (http://www.ncbi.nlm.nih.gov/pubmed/11505469), a difference in lung size (http://aje.oxfordjournals.org/content/160/9/893.full.pdf), or a combination of these differences. This would not be to imply that blacks have a selective disadvantage: the greater bone density of blacks may mean significantly less incidence of osteoporosis (http://www.ncbi.nlm.nih.gov/pubmed/21431462).

The average weight of a young man with the given densities per the study is about 80 kg or 175 lbs.

For an 80 kg black man, his volume is: 80 kg/(1.075 g/mL)= 74.4 L

For an 80 kg white man, his volume is: 80 kg/(1.065 g/mL)= 75.1 L

It is a difference of 0.7 L, or 0.7 L*(1.07 g/mL) = 750 g = 1.65 lb of extra buoyancy force for whites than for blacks.

So, the average black man in a swimming pool is like the average white man but wearing an extra 1.65 lb or gold chains (I choose gold chains for their very high density, not for the racial caricature). Doesn't seem like so much, but it makes a bigger difference when looking at the right tail ends of the body density distributions of each race.

Given a racial density difference of 0.01 g/mL, this means the average body densities of whites and blacks are about 0.83 white standard deviations apart and about 0.66 black standard deviations apart.

Using a z-score calculator (https://www.fourmilab.ch/rpkp/experiments/analysis/zCalc.html), assuming an extra weight of 1.65 lb, with z=0.66 black standard deviations, Q is 0.25, and it means that 75% of blacks are like the average white but with at least an extra 1.65 lb of gold chains. With z=0.83 white standard deviations, Q is 0.20, so only 20% of whites are like the average white with at least an extra 1.65 lb of gold chains.

Now we look at the right tail ends. What if it is a body density equal to an extra 5-pound weight of gold chains? For whites, this is 5 lb*(0.83 SD/1.65 lb)= 2.52 standard deviations above the white mean. This means Q is 0.005868, or 1 in 170. One in 170 whites have a body density equal to an extra 5-pound weight in gold chains. But, for blacks, this is 5 lb*(0.66 SD/1.65 lb)= 2 black standard deviations above the white mean and equal to 2 minus 0.66 black standard deviations equals 1.33 black standard deviations above the black mean. Another way to calculate this is that 5 pounds of extra weight for the average white is just 5-1.65=3.35 pounds of extra weight for the average black, and 3.35 lb*(0.66 bSD/1.65 lb) = 1.34 black standard deviations above the black mean. For z=1.34, this means Q is 0.090123 or 1 in 11.

So:

1 in 11 black men is like the average white man but with an extra five-pound weight in gold chains, and this is 15 times as many blacks as whites.

The amount of air in the lungs needed to compensate for five pounds worth of extra density is:

5 lb/(density of fluid) = 2.26 kg/(1 kg/L) = 2.3 L

So, 2.3 extra liters of air are needed to compensate for five extra pounds of gold chains. The extra air intake above normal intake from extra inhalation is 3.0 liters (IRV = 3.0 L per http://www12.homepage.villanova.edu/thomas.chubb/anatomy/S04/Measurements04.htm), an intermediate portion of which is typically necessary to achieve positive buoyancy, as all human bodies at rest are denser than water; without taking in an extra breath of air while swimming, you are more likely to sink. The 2.3 L is a significant cut.

Therefore, American blacks are much more likely to drown than American whites.

None of this is to claim that differences in average body density is the dominant explanation for any and all group differences. Differences in psychological swimming ability also have a significant effect, and they PROBABLY have an effect on the racial drowning differences. But, if there exists differences in psychological swimming ability between the races, then differences in average body density would likewise predict that, too: you are less likely to learn to swim if such learning is physically more difficult. And, regardless, any significance of such an explanation does not minimize the predictive power of the data concerning body densities and the physical predictions that follow.

So, how can this information be useful? Spot the drowning child.



Full story at The Daily Mail.
 
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What's the point, and why on earth do you believe such a small difference in bouyancy force is significant? Statistical significance is one thing in establishing the actual difference in buoyancy, but the relation to drowning seems spurious for a difference that small.

What if blacks have reduced lung capacity due do disproportionately poorer air quality in impoverished communities? What if lifeguards/paramedics/first responders have a racist streak? What if whites are less likely to partake in swimming to begin with?

And why the hell are "gold chains" your unit of measurement? If you're going to try to pass off racism as science, at least use real units of measurement.
 

Tannhauser

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Yeah why did you pick gold chains? You could have picked anything, like guns or baggies filled with narcotics.

I am joking..

I checked your math on the tail calculation, it seems correct (except using more precise numbers I got 1.36 std for the blacks instead of 1.34). Although one comment: it is not correct to say that there are 15x as many blacks as whites who have that density. You need to multiply that with the ratio of the number of blacks vs whites in total.
 

ApostateAbe

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What's the point, and why on earth do you believe such a small difference in bouyancy force is significant? Statistical significance is one thing in establishing the actual difference in buoyancy, but the relation to drowning seems spurious for a difference that small.

What if blacks have reduced lung capacity due do disproportionately poorer air quality in impoverished communities? What if lifeguards/paramedics/first responders have a racist streak? What if whites are less likely to partake in swimming to begin with?

And why the hell are "gold chains" your unit of measurement? If you're going to try to pass off racism as science, at least use real units of measurement.
A small difference between either the averages of two bell-curved distributions or the standard deviations makes for an unexpectedly large relative difference in the right tail ends. That is the principle that leads to the conclusion I put in large font: 1 in 11 black men is like the average white man but with an extra five-pound weight in gold chains, and this is 15 times as many blacks as whites. I use gold chains not for the racial caricature but because gold has an especially high density, so five pounds of gold chains is approximately equal to five pounds of downward net force in the water. That isn't to say the ambiguous racism of gold chains isn't fun. I was banned from a physics forum in part for that reason.
 

ApostateAbe

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Yeah why did you pick gold chains? You could have picked anything, like guns or baggies filled with narcotics.

I am joking..

I checked your math on the tail calculation, it seems correct (except using more precise numbers I got 1.36 std for the blacks instead of 1.34). Although one comment: it is not correct to say that there are 15x as many blacks as whites who have that density. You need to multiply that with the ratio of the number of blacks vs whites in total.
I want to get my math right, but I am not sure what you mean by "You need to multiply that with the ratio of the number of blacks vs whites in total." Maybe you can give your own equations or something.
 
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A small difference between either the averages of two bell-curved distributions or the standard deviations makes for an unexpectedly large relative difference in the right tail ends. That is the principle that leads to the conclusion I put in large font: 1 in 11 black men is like the average white man but with an extra five-pound weight in gold chains, and this is 15 times as many blacks as whites. I use gold chains not for the racial caricature but because gold has an especially high density, so five pounds of gold chains is approximately equal to five pounds of downward net force in the water. That isn't to say the ambiguous racism of gold chains isn't fun. I was banned from a physics forum in part for that reason.
Yes, your data shows without a doubt that the bodies of blacks are slightly more dense than whites. We all get that.

Your data says jack shit about drowning. If anything, you've shown that whites have more body fat or heads full of air. Whoop de doo.
 

Hadoblado

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I'm not so unforgiving of the idea, but using gold chains hurts the product of your efforts, even if you do find it fun.

I've never actually heard the stereotype, but I guess Australian blacks might be fairly different. If anything I would have predicted them being better swimmers due to general all-round athleticism.
 

ApostateAbe

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Yes, your data shows without a doubt that the bodies of blacks are slightly more dense than whites. We all get that.

Your data says jack shit about drowning. If anything, you've shown that whites have more body fat or heads full of air. Whoop de doo.
Drowning happens when people's heads go below the surface of the water and do not come back up. If it is physically much easier for some people's heads to go below the water than other people's, then the peoples are more likely to drown. Maybe you have been swimming, and you may have noticed that you can lay flat on your back and float on the surface of the water after taking in a breath of air. Some people can't do that. They take in a breath of air, and they still sink like a rock. I had a Nigerian colleague in grad school who attempted to learn to swim. He could not. He always sank like a rock. I wish I had known the reason for this. Because he was stupid? Because he didn't have the right teacher? No. Body densities make a big difference, it is directly expected from the physics, and it is not common knowledge but it should be. It is likely the same primary cause of why males are three times more likely to drown than females. At the very least, such knowledge can be used to inform lifeguards of how to direct their attention. Should you pay more attention to the black boy or the white girl? The black boy is nine times more likely to drown. Not that you should completely ignore the white girl, but let's be real.
 

ApostateAbe

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I'm not so unforgiving of the idea, but using gold chains hurts the product of your efforts, even if you do find it fun.

I've never actually heard the stereotype, but I guess Australian blacks might be fairly different. If anything I would have predicted them being better swimmers due to general all-round athleticism.
I don't have any kind of data for Australian aborigines. They would be a totally different race from West Africans (Congoids), though a similar skin color.
 
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Drowning happens when people's heads go below the surface of the water and do not come back up. If it is physically much easier for some people's heads to go below the water than other people's, then the peoples are more likely to drown. Maybe you have been swimming, and you may have noticed that you can lay flat on your back and float on the surface of the water after taking in a breath of air. Some people can't do that. They take in a breath of air, and they still sink like a rock. I had a Nigerian colleague in grad school who attempted to learn to swim. He could not. He always sank like a rock. I wish I had known the reason for this. Because he was stupid? Because he didn't have the right teacher? No. Body densities make a big difference, it is directly expected from the physics, and it is not common knowledge but it should be. It is likely the same primary cause of why males are three times more likely to drown than females. At the very least, such knowledge can be used to inform lifeguards of how to direct their attention. Should you pay more attention to the black boy or the white girl?
The black boy is nine times more likely to drown. Not that you should completely ignore the white girl, but let's be real.
Nigga, until you start throwing thousands of people in rivers and seeing who swims out alive and in what numbers, you can't say a thing about who's more likely to drown.
 

ApostateAbe

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Nigga, until you start throwing thousands of people in rivers and seeing who swims out alive and in what numbers, you can't say a thing about who's more likely to drown.
Yes I can. The statistics are freely available.
 

redbaron

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I thought this was already well documented? That African-Americans have a higher bone density on average, as well as a higher capacity for it which in turn affects their swimming ability but also improves their ability to build functional muscle mass (as in, their bones can hold more).

As for how much it affects swimming ability:

http://www.bloombergview.com/articles/2015-03-26/black-swimmers-sweep-away-a-stereotype

To note though, high performance athletes generally circumvent biological norms. In terms of averages it's entirely possible that black people are worse swimmers as a result of decreased buoyancy. Just like on average men are taller than women.

It's not racist or sexist.
 

Brontosaurie

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obviously he has no source since this hasn't been studied. in my view he is offering arguments in favor of a hypothesis which seems to hold some scientific and medical potential. that's the content of this thread. why bother having issues with his convinced "tone" or whatever it is?
 

ApostateAbe

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Peer reviewed source specifically stating that blacks drown at an increased rate due to higher body density?

"Hey, look! Correlations and anecdotes!"
My research has led me to the belief that body density variations are totally ignored as a potential cause of differences of drowning rates. It could be because it is too late to measure the body density of someone who died from drowning, and/or it would be of little interest to the family of the deceased. Not only is the literature silent about whether or not the causes of the racial differences in drowning rates could be body densities differences, but they are silent about any sort of cause of it. It leaves a lot of members of the public just talking out their asses about it, and of course they tend to totally ignore the physics, because we are all past the point of believing in something as ridiculous as relevant physical differences between the races.
 
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My research has led me to the belief that body density variations are totally ignored as a potential cause of differences of drowning rates.
It could be because it is too late to measure the body density of someone who died from drowning, and/or it would be of little interest to the family of the deceased. Not only is the literature silent about whether or not the causes of the racial differences in drowning rates could be body densities differences, but they are silent about any sort of cause of it. It leaves a lot of members of the public just talking out their asses about it, and of course they tend to totally ignore the physics, because we are all past the point of believing in something as ridiculous as relevant physical differences between the races.
Lol... Your research didn't even factor in basic shit like lifeguard presence or pool depth. The most important factors in a drowning are clearly race and income: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1470565/
 

ApostateAbe

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Tannhauser

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I want to get my math right, but I am not sure what you mean by "You need to multiply that with the ratio of the number of blacks vs whites in total." Maybe you can give your own equations or something.
Well, it was a simple point: what has been shown by your calculations is that a black person is 15 times as likely to have that particular body density as a white person.That does not mean there are 15 times as many blacks with that density as whites in the population, because it depends on how many black vs whites there are.

It is an interesting point that there is a difference between body densities, but whether the density itself has any effect on the probability on drowning is an essential question. That is a question completely independent of the difference between races. It might also be that the extra density is due some factor that actually increases the chance of surviving, instead of the opposite (maybe the extra density comes from muscles which can be used for swimming etc). So i dont think you can prove or disprove anything with the numbers you have.
 

Grayman

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Lol... Your research didn't even factor in basic shit like lifeguard presence or pool depth. The most important factors in a drowning are clearly race and income: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1470565/
That is a horrible, biased, and incorrect analysis. A black is 4 times more likely to drown than a Hispanic while Hispanics have a lower income on average than blacks.

black = 47%chance
white = 33%
hispanic = 12%

BUT they don't care about that. They only care to compare whites and blacks.... why do you think that is?

I think Hispanics have the advantage of shorter appendages in comparison to wider chest cavities. And yes Redbaron is right about bone density.
 
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"Poisson regression analysis showed that race (P< .0001) but not income (P= .60) was an independent predictor of drowning rates in models that included age, gender, race, and income."
Try harder. In addition to ignoring such completely superfluous factors as pool depth and lifeguard presence:
However, because death certificates were our primary data source, other potential contributing factors were not consistently reported (e.g., substance use). Also, lack of exposure data allowed us to only make a general estimate on the risk for drowning. More information on how much time children in different ethnic groups spend in pools is necessary to calculate a true determination of risk. Finally, because we used a proxy indicator of income, we were unable to adjust for individual income to determine the extent to which income as a proxy for socioeconomic status mediated the association between race and drowning.
Citing bad science doesn't make it good science. Whoever designed this experiment needs shot and fired, not necessarily in that order. (Figuratively. Jeesus, before the feds show up at my doorstep)
 
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That is a horrible, biased, and incorrect analysis. A black is 4 times more likely to drown than a Hispanic while Hispanics have a lower income on average than blacks.

black = 47%chance
white = 33%
hispanic = 12%

BUT they don't care about that. They only care to compare whites and blacks.... why do you think that is?

I think Hispanics have the advantage of shorter appendages in comparison to wider chest cavities. And yes Redbaron is right about bone density.
Nah. Hispanics clearly have an advantage because of all the gas in their bowels from the beans in their diet.

Troof. I've seen the correlation with my own eyes.

Your sarcasm detector needs new batteries.
 

ApostateAbe

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Well, it was a simple point: what has been shown by your calculations is that a black person is 15 times as likely to have that particular body density as a white person.That does not mean there are 15 times as many blacks with that density as whites in the population, because it depends on how many black vs whites there are.

It is an interesting point that there is a difference between body densities, but whether the density itself has any effect on the probability on drowning is an essential question. That is a question completely independent of the difference between races. It might also be that the extra density is due some factor that actually increases the chance of surviving, instead of the opposite (maybe the extra density comes from muscles which can be used for swimming etc). So i dont think you can prove or disprove anything with the numbers you have.
It may be just a misunderstanding, and I should be clearer, maybe if I express it this way:

1 in 11 black men is like the average white man but wearing an extra five pounds of gold chains, whereas only 1 in 170 white men is like the average white man but wearing an extra five pounds of gold chains. This is a 15-fold difference.

This is talking only about the right-tail-ends of the racial body density distributions, not the peaks of those distributions.

Good point about muscle mass. Maybe if the body density differences were all about muscle mass, it would be a helpful effect instead of a drowning effect. There are three potential causes of the racial body density differences--muscle mass, lung size, and bone density--and I have not done a mathematical analysis to find which difference has the greatest effect, though maybe I can. I suspect it is lung size. If so, that would most certainly increase drowning rates among blacks (elite swimmers tend to have larger lungs).
 
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The majority of Black victims (51%) drowned in public pools, the majority of White victims (55%) drowned in residential pools, and the majority of Hispanic victims (35%) drowned in neighborhood pools (e.g., an apartment complex pool).
Depth differences between pool types alone would likely make this unpublishable, forget about the lifeguards.
 
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