Hard to tell if this has always been the case, since for the first 100+ years of our history, lefties were forcefully converted into righties. But looking at recent history, 47% of US presidents being left handed is statistically significant and cannot be coincidence.
I’ve always understood left-handedness and IQ to have a bimodal distribution. There are both disproportionately more geniuses and mentally retarded people who are left-handed. Non-right-handedness is also associated with an assortment of neurological conditions. I know the right-brain/left-brain stuff has been largely debunked, but there does seem to be something unusual about left-handedness.
I also seem to recall that there is evidence that fetuses who are exposed to more testosterone in-utero are more likely to exhibit non-right-handedness. Testosterone, of course, is associated with masculinity. Perhaps among men who have a decent shot at being president, the ones who the most masculine are preferred by the voting population. Which makes sense. Tall guys have an advantage over shorties. Guys with deep, resonated voices seem more “presidential” than guys with peepsqueak voices. And guys who the most assertive/aggressive are more likely to rise to the top than guys who aren’t.
The office of the presidency, in other words, may be selecting for qualities of uber maleness. Left-handedness would then naturally follow.
(It would be interesting to look at the degree of left-handedness of CEOs, both male and female.)
There could be some connection, but it’s an extremely small sample size. The smaller your sample, the greater the possibility that your results are due to coincidence. If you look at the blood types of the last 15 presidents chances are good that they won’t fall neatly into the percentages you’d expect to find in the public at large, but the fact that there are more of them that were type O than you’d find in the general population doesn’t necessarily mean that having type O blood is presidential.
Now that’s interesting and could explain things, but I can’t find any reliable data to support the theory that left-handed dominance & genius are related.
I’ve also googled to see if it is more likely for other world leaders to be left-handed, but it’s a really hard thing to draw any conclusions on because there are often cultural stigmas that go way back (I think there are biblical passages that suggest some sort of evil being associated with the left hand).
And pravnik, anything’s possible but it seems too unusual to be chalked up to random chance. Especially when you consider that (1) presidents in the first half of our history were forced to be righties; (2) even when schools stopped forcing right-handedness there was still a stigma; (3) the stigma (as far as I know) is now gone and 5 out of the past 7 US presidents were left handed.
I just plugged the last 5 out of 7 presidents being left-handed into your calculator and got 0.0001 probability that it’s random. Cool.
that calculator does not measure statistical significance. the rule of thumb in statistics is not to even bother with anything with a sample under 100. Nor is the sample random in any sense of the word: the past 15 is deliberately chosen because it happens to have a lot of left handed people. If you took ALL of the presidents, then maybe you could run some numbers. But statistical significance isn’t the same as the probability something would happen by chance. If I flip a quarter and it comes up heads all 4 times, the probability that would happen by chance is very low, but it doesn’t make it statistically significant.
I agree that 15 is an insignificant sample size, but it does seem incredible that it could be random chance.
And I did not choose the past 15 presidents to analyze “because it happens to have a lot of left handed people”, but rather because reliable info is hard to come by from earlier presidents, given that educated people at the time were forcefully made to be right handed.
Small sample sizes are hard to work with, but that’s all we’ve got when it comes to US presidents.
There are many thousands of different traits could you compare for past presidents. The likelihood that some of them would have significant deviation from average distribution is very high.
Also, it’s not a random sample. Two of our last presidents are directly related.
Well, of course not. But to claim that the high incidence of left-handedness among recent presidents is entirely due to chance (not that anybody has claimed this) is equivalent to claiming that recent presidents function as a random sample as far as handedness is concerned. And I was curious what the implications of that assumption would be. That’s all I was doing.
So of course I had to check the link: those two have different handednesses.
Sure, and I bet there are even longer odds against three of the first five presidents dying on July 4th. But there are all kinds of things that wacky coincidences can be made of, so it’s not that improbable that something that looks like a wildly unlikely coincidence will turn up among any given set of presidents. If not a cluster of left-handed presidents, we could have had a string of red-headed ones, or Tauruses, or ones whose middle name started with H, or what-have-you, and somebody on a message board in this alternate universe would be speculating about the odds against this phenomenon.
Does that even make sense? I guess what I’m saying is that the odds against any particular coincidence might be long, I’d guess that you can find some sort of odd pattern or coincidence among almost any given group of people.
For certain hypothesis tests and levels of confidence, that is not true.
However, I’m given to the null hypothesis for presidents, since whatever mechanism I can hypothesize* would lead me to predict higher levels of left-handedness for governors, too, which appears to not be the case.
*Basically, the same mechanism that I think others are positing - left-handedness genes are ‘close to’ genes that affect Q intelligence, or ambition, or other factors that clearly lend themselves to high executive office.
Yes, I checked too and if the Bushes were both lefties, I would have thrown one or both of them out due to genetics. But W was a rightee
I am not necessarily suggesting anything…but IMO there does seem to be more to this than mere coincidence. I started paying attention to this leftie trend in 1992, when all 3 presidential candidates were left handed. Then, when Obama ran against McCain, both of them were lefties too.
(Clinton ran against Bob Dole in 96, but Dole was left handed due to a right arm injury)
And, Bup, interesting point on the governors…
So a question for you statisticians out there: at what point would consider that there may be something more to this than coincidence? Or can conclusions never be drawn about US presidents, given the small sample size?
I still find it remarkable that 10% of the population is left handed, but a significantly higher percentages of presidents are left handed. Is there a statistician in the house that can quantify what the odds of such a coincidence would be?
I tend to work with relatively small sample sizes (n<30). In my line of work, you rarely have a whole lot of data to work with. You will never have an ideal number of samples. There comes a point when you decide to sacrifice a little certainty just so you can say something when your boss asks, “What’s the dealio?” But then again, it’s not like the conclusions I make have urgent life-and-death consequences. I rarely have to have high confidence before I make a conclusion. Tis the beauty of environmental science.
I think if there’s something special about left-handedness and positions of power, the pattern would emerge in other arenas besides US presidents. What’s the handedness ratio of Congress critters, Fortune 500 CEOs, middle school student councils, etc. If you look at the heads of state internationally, do you find a similar skew? Maybe left-handedness and US presidency is a spurious correlation. For instance, many of the presidents were from the South. If Southerners are more likely to be lefties than Northerners are, it wouldn’t be that surprising if more presidents were “lefty” than you’d expect. But if an examination of other groups of leaders reveals a similar pattern, then your weight of evidence just got heftier.
There is evidence to support the claim that left-handedness shows up more frequently in US presidents than the general population. It’s just that you need a whole lot more data to say that there is a significant relationship between handedness and presidency.
It would seem that whatever attracts lefties to the presidency, it’s something that has to be unique not just to leadership roles and not just the presidency, but to the presidency of the United States specifically.