In the United States, Missouri has always been known as the bellwether state for its ability to elect the correct candidate in all presidential elections since 1904, barring 1956 and 2008. Many possible causes are given for this ability; here are the principal ones:
- Missouri has St. Louis in the east, and Kansas City in the west, which tend to vote Democrat, with a middle that tends towards Republicans.
- Missouri is in the mean population center of the United States.
- Missouri has a mix of urban, suburban and rural citizens.
- Missouri fought on both sides of the Civil War.
With this last reversal however (Missouri chose McCain while the nation voted for Obama), this status is being put into question since states such as Ohio, Pennsylvania, California and New Mexico have all claimed to be more precise.
We therefore asked ourselves how much of a rarity it is to elect the correct candidate in every election over a century. After all, that is 25 elections and with a choice of 50 states and only 2 parties to choose from each time, it does not seem too far-fetched that at least one of them will be correct every time even just by chance – probabilistically speaking.
So is all the talk of possible causes just hullabaloo? Is it likely to have one state pick the correct candidate so often? Or is Missouri, or whichever other state supersedes it, correct in being so proud of its status and searching for the causes?
We decided to put this to the test by use of a not-so-simple calculation:
1-(1-p^T)^N
Where:
p = Probability of choosing the correct candidate = 50%
N = Number of States = 50
T = Number of Elections = 25
As you can see by running this calculation, the probability of any one state being correct for all 25 elections is 0.000149%
So it turns out that a bellwether state is something to be taken very seriously if and when it emerges since, purely probabilistically speaking, they will sprout up only 1 ten thousandth of a percent of the time.
