photo credit: BL1961
photo credit: BL1961
There have been several stories in the media about the remarkable number of left-handed presidents in recent decades (Gerald Ford, Reagan, the elder Bush, Clinton and Obama all were Southpaws; and even many candidates and VPs were, such as John McCain and Al Gore).
As a lefty myself I feel a bit flattered that some of these stories cite brain research indicating that left-handedness may give us an edge with language, visualizing problems and dealing with complexity.
I haven’t found, however, precise information about the statistical probability of having exactly 5 left-handed presidents in a particular series of 7.
So what are those chances if lefties and righties were equally likely to end up in the oval office?
Left-handed folks make up approx. 10 percent of the general population. Correct me if I’m wrong, but this seems to be the kind of “k out of N” statistical situation involving “binomial probability” that my math teacher Herr Ernst taught me about back in high school. I think I haven’t applied this since. Below is the formula to calculate the chances to have exactly k hits among N events with p being the chances for a hit, and q the odds for a miss:
P(k out of n) =
|
n!
k!(n-k)!
|
(pk)(qn-k) |
This Web page allows to simply plug in the values for p, q, N and k and does all the calculations for you.
If you do the math you get the following. The chances for having exactly 5 lefties in a given series of 7 presidents are 0.00017010000000000012, i.e. approx. one in 5,878 such “seven series” (the chances of having at least 5 lefties (i.e. 5 or 6 or 7 lefties in a series of 7) are, of course, only a bit more: 0.00017650000000000012, i.e. one in 5,666 “seven-series”).
So there you have it: If all were equal (i.e. if lefties and righties were equally likely to make it to the Oval Office), it would be quite unlikely to have so many left-handed presidents.
Then again, flukes do happen. To be scientific we would really have to look at a larger sample of Presidents. Looking to the past may not help much, since it used to be that natural lefties would be forced at an early age to use their right hands. So we will never know which of all the 44 presidents might have been left-handed had nature been allowed to run its course.
Imagine my delight when I saw a “
