Comments on: Center of Population http://blag.xkcd.com/2008/05/01/center-of-population/ The blag of the webcomic Sat, 07 Nov 2009 17:16:41 +0000 http://wordpress.org/?v=2.8.4 hourly 1 By: noone http://blag.xkcd.com/2008/05/01/center-of-population/comment-page-5/#comment-30706 noone Thu, 03 Sep 2009 11:52:47 +0000 http://blag.xkcd.com/2008/05/01/center-of-population/#comment-30706 I think it's the average deviation from the average length of the path from each person to the center that's being minimized i.e. if the school is at the center of population then every pupil will have roughly the same distance to travel to school. Example in a one-dimensional world: There are two people at point A and one person at point B, 30 km away. The best place for the school to optimize for distance would obviously be point A. The two persons there would be living inside the school and the person at B would have to travel 30 km, thus the average would be (0km+0km+30km)/3=10km. The average deviation from that would be ((10+10+20)/3)km = 13,3km. If the school is at the center of population C, between A and B, 10km away from A, then the average way would be ((10+10+20)/3)km = 13,3km > 10km, but the average deviation would only be ((3,3+3,3+6,7)/3)km = 4,43 km < 13,3km. So this would be the <i>fairest</i> point to build a school, but not the best. I think it’s the average deviation from the average length of the path from each person to the center that’s being minimized i.e. if the school is at the center of population then every pupil will have roughly the same distance to travel to school.

Example in a one-dimensional world: There are two people at point A and one person at point B, 30 km away. The best place for the school to optimize for distance would obviously be point A. The two persons there would be living inside the school and the person at B would have to travel 30 km, thus the average would be (0km+0km+30km)/3=10km. The average deviation from that would be ((10+10+20)/3)km = 13,3km.

If the school is at the center of population C, between A and B, 10km away from A, then the average way would be ((10+10+20)/3)km = 13,3km > 10km, but the average deviation would only be ((3,3+3,3+6,7)/3)km = 4,43 km < 13,3km.

So this would be the fairest point to build a school, but not the best.

]]> By: radyo dinle http://blag.xkcd.com/2008/05/01/center-of-population/comment-page-5/#comment-29768 radyo dinle Sun, 19 Jul 2009 14:57:04 +0000 http://blag.xkcd.com/2008/05/01/center-of-population/#comment-29768 I don’t think the center of mass is the correct stuff to use for the location of school problem. Simple reason being that all the heavier kids would get more weight in the equation. other reason being that I wasn’t particularly weighty as a kid. of course that equation might help in reducing the sum of work done to get to school by the kids. I don’t think the center of mass is the correct stuff to use for the location of school problem.
Simple reason being that all the heavier kids would get more weight in the equation.
other reason being that I wasn’t particularly weighty as a kid.
of course that equation might help in reducing the sum of work done to get to school by the kids.

]]> By: Filim izle http://blag.xkcd.com/2008/05/01/center-of-population/comment-page-5/#comment-29569 Filim izle Sat, 11 Jul 2009 21:01:14 +0000 http://blag.xkcd.com/2008/05/01/center-of-population/#comment-29569 Fillim.net sitemiz full online film seyretmeniz için haz?rlanm??t?r.. Fillim.net sitemiz full online film seyretmeniz için haz?rlanm??t?r..

]]> By: Alexx http://blag.xkcd.com/2008/05/01/center-of-population/comment-page-5/#comment-26078 Alexx Tue, 24 Mar 2009 12:12:15 +0000 http://blag.xkcd.com/2008/05/01/center-of-population/#comment-26078 nice post <a href="http://megaplus.com.ua" title="??????? karcher, ???????? karcher ????, ?????? karcher ds 5500 ds 5600 ?????? sv 1802" rel="nofollow"></a> nice post

]]> By: Ben W http://blag.xkcd.com/2008/05/01/center-of-population/comment-page-5/#comment-25482 Ben W Mon, 16 Feb 2009 07:42:42 +0000 http://blag.xkcd.com/2008/05/01/center-of-population/#comment-25482 I think Johan is right! I've thought of a number of tricky scenarios to try and fool it, but it succeeds every time. This is of course assuming that you want to find a point on the surface of the Earth which minimises distance across the surface to every person. The way to solve it would be to minimise the sum of all the (mgh)s. Or just plain (mh)s, given that g is just a constant. And come to think of it, since we're assigning equal value to each person, we could just minimise h. Granted, h is still a function of both theta and phi. I think Johan is right! I’ve thought of a number of tricky scenarios to try and fool it, but it succeeds every time. This is of course assuming that you want to find a point on the surface of the Earth which minimises distance across the surface to every person. The way to solve it would be to minimise the sum of all the (mgh)s. Or just plain (mh)s, given that g is just a constant. And come to think of it, since we’re assigning equal value to each person, we could just minimise h. Granted, h is still a function of both theta and phi.

]]> By: damian http://blag.xkcd.com/2008/05/01/center-of-population/comment-page-5/#comment-20673 damian Thu, 25 Sep 2008 03:30:36 +0000 http://blag.xkcd.com/2008/05/01/center-of-population/#comment-20673 My intuitive assessment is that the centre of everything is located approximately a meter and a half to the left of me, +- a couple of meters, although i can think of no obvious proof of this. My intuitive assessment is that the centre of everything is located approximately a meter and a half to the left of me, +- a couple of meters, although i can think of no obvious proof of this.

]]> By: uberben http://blag.xkcd.com/2008/05/01/center-of-population/comment-page-5/#comment-20132 uberben Thu, 11 Sep 2008 01:54:28 +0000 http://blag.xkcd.com/2008/05/01/center-of-population/#comment-20132 Since I got in on this thread late, I have not read all the comments, but I have a theory that might be able to be expanded for finding the "center of population" inside a sphere. Instead of imagining every person on the planet having a uniform mass, they can each have a uniform tension on the center of population. Picture you are inside a giant beach ball with a number of similar rubber bands connected to the shell of the ball at one end and each other at the other. This central knot will be pulled to a central point where the tension to each point on the shell is the least. A similar method idea could work where a person is at each point on the shell where a band is connected. Can anyone think of a way to find where the knot would be? Since I got in on this thread late, I have not read all the comments, but I have a theory that might be able to be expanded for finding the “center of population” inside a sphere. Instead of imagining every person on the planet having a uniform mass, they can each have a uniform tension on the center of population. Picture you are inside a giant beach ball with a number of similar rubber bands connected to the shell of the ball at one end and each other at the other. This central knot will be pulled to a central point where the tension to each point on the shell is the least. A similar method idea could work where a person is at each point on the shell where a band is connected. Can anyone think of a way to find where the knot would be?

]]> By: Jon http://blag.xkcd.com/2008/05/01/center-of-population/comment-page-5/#comment-19326 Jon Mon, 07 Jul 2008 19:20:17 +0000 http://blag.xkcd.com/2008/05/01/center-of-population/#comment-19326 I found the center of population on the surface of the earth to be at 30.89N,76.53E. I found this by calculating the weighted average distance a given point was from all the people on the earth until I found the smallest average distance. I did this at a resolution of 1 degree latitude and 1 degree longitude around the entire earth. Then I increased the resolution and decreased the search area to get the values I got. It turns out that the average person is 5032 km from this point. I also recorded the average distance for all 65,000ish points, so I could make a map showing the average distance everyone is from a given point, but I'm not sure how to make the map. I also found the center of population based on a center of mass calculation and found that, assuming everyone weighs the same, the center of mass is 637 km under 15.68N,75.60E. I found the center of population on the surface of the earth to be at 30.89N,76.53E. I found this by calculating the weighted average distance a given point was from all the people on the earth until I found the smallest average distance. I did this at a resolution of 1 degree latitude and 1 degree longitude around the entire earth. Then I increased the resolution and decreased the search area to get the values I got. It turns out that the average person is 5032 km from this point. I also recorded the average distance for all 65,000ish points, so I could make a map showing the average distance everyone is from a given point, but I’m not sure how to make the map. I also found the center of population based on a center of mass calculation and found that, assuming everyone weighs the same, the center of mass is 637 km under 15.68N,75.60E.

]]> By: caffeine effects on babies http://blag.xkcd.com/2008/05/01/center-of-population/comment-page-5/#comment-19324 caffeine effects on babies Mon, 07 Jul 2008 17:07:19 +0000 http://blag.xkcd.com/2008/05/01/center-of-population/#comment-19324 <strong>caffeine effects on babies...</strong> Sorry, don't agree 100% with you on this!... caffeine effects on babies…

Sorry, don’t agree 100% with you on this!…

]]> By: Jonathan Birge http://blag.xkcd.com/2008/05/01/center-of-population/comment-page-5/#comment-19208 Jonathan Birge Fri, 27 Jun 2008 06:50:22 +0000 http://blag.xkcd.com/2008/05/01/center-of-population/#comment-19208 200 comments for an idea which is stupid for the following reason: with your definition, the point is not neccesarily unique on a periodic surface. For example, imagine a world uniformly distributed with people. All points fit your definition. Certainly, in our current world, a lot of points probably do to a decent approximation. It's a dumb idea, certainly far dumber than 200 comments would warrant. Let's move on, people. 200 comments for an idea which is stupid for the following reason: with your definition, the point is not neccesarily unique on a periodic surface. For example, imagine a world uniformly distributed with people. All points fit your definition. Certainly, in our current world, a lot of points probably do to a decent approximation. It’s a dumb idea, certainly far dumber than 200 comments would warrant. Let’s move on, people.

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