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Just for curiosities sake I fell down the rabbit hole and ran the numbers (please someone correct me if I'm wrong on this - it's been a loooooong time since I d

Just for curiosities sake I fell down the rabbit hole and ran the numbers (please someone correct me if I'm wrong on this - it's been a loooooong time since I did statistics). This is all assuming some sort of even distribution of land/water, so the numbers don't reflect real world continental distribution, but I don't know how to account for that. We have a 30% chance of picking a random point on Earth and getting land. Because earth is so big and these theoretical points are so small I'm going to assume that one point of land existing doesn't effect the odds of another piece of land existing. So that's two antipodal points, each with a 30% chance of being land. Putting that into a probability calculator (again, long time since statistics) that gives us odds of both point A & B being land as 9%. If we flip that around and go with the 30% land and 70% water odds we end up with a chance of 21%. It seems like there's actually MORE land that's antipodal to other land than we'd expect statistically? I must have some bad math here.

jameshart 4y ago
(Edit - I misread my own math here) Not sure where 21% comes from - if 3/10 of points are on land, 9/100 antipode-pairs should be land-land, and that means 9/100 / 30/100 = 9/30 = 30% of land should have land opposite it, and conversely 70% should have water? But the true numbers are 15%/85% - on the actual earth, land is more likely to have ocean opposite it than random chance would suggest. Analyzing whether items sufficiently far from the ‘expected’ random distribution as to be statistically significant is a rather different exercise though.
- deleted 4y ago
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addaon 4y ago
> We have a 30% chance of picking a random point on Earth and getting land. Because earth is so big and these theoretical points are so small I'm going to assume that one point of land existing doesn't effect the odds of another piece of land existing. This is the issue. A large contributor of the "point antipodal to land is water" anomaly is the typical size of land masses. If, for example, the average size of land masses was 30% of earth's area, then we'd have a single large land mass (Pangaea style), and all antipodal points would be water. The approximation of independence here doesn't reflect reality. Eurasia alone is more than 10% of the land area of Earth.
- SketchySeaBeast 4y ago
  There we go - where land appears, it clumps.

jameshart 4y ago

(Edit - I misread my own math here) Not sure where 21% comes from - if 3/10 of points are on land, 9/100 antipode-pairs should be land-land, and that means 9/100 / 30/100 = 9/30 = 30% of land should have land opposite it, and conversely 70% should have water? But the true numbers are 15%/85% - on the actual earth, land is more likely to have ocean opposite it than random chance would suggest. Analyzing whether items sufficiently far from the ‘expected’ random distribution as to be statistically significant is a rather different exercise though.

deleted 4y ago
[deleted]

addaon 4y ago

> We have a 30% chance of picking a random point on Earth and getting land. Because earth is so big and these theoretical points are so small I'm going to assume that one point of land existing doesn't effect the odds of another piece of land existing. This is the issue. A large contributor of the "point antipodal to land is water" anomaly is the typical size of land masses. If, for example, the average size of land masses was 30% of earth's area, then we'd have a single large land mass (Pangaea style), and all antipodal points would be water. The approximation of independence here doesn't reflect reality. Eurasia alone is more than 10% of the land area of Earth.

SketchySeaBeast 4y ago
There we go - where land appears, it clumps.