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The Central Limit Theorem Visualized with D3

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Re: The Central Limit Theorem Visualized with D3

#21
post #5

This isn't the central limit theorem. This is a binomial distribution. Nice animation though.

It does illustrate a special case of the CLT, in the sense that as the number of bins increases, the distribution (the mean of a bunch of +1/-1 Bernoulli random variables) converges to a normal distribution.

Re: The Central Limit Theorem Visualized with D3

#22
Kind of a misleading animation, since n is the number of switches (4) and not the number of balls (which diverges to infinity).

Setting the bins to 500 froze the browser, unfortunately.

The physical machines that do this are undeniably cool, but especially when they have the curve painted on beforehand; this is the best I could find right now, but I remember seeing a pretty big one as part of a traveling mathematics museum exhibition:

http://www.youtube.com/watch?v=AUSKTk9ENzg

Re: The Central Limit Theorem Visualized with D3

#24
post #10
post #5

This isn't the central limit theorem. This is a binomial distribution. Nice animation though.

It is the distribution of the average of n binomial distributions (taking on values x±1)†, which according to the CLT converges to a Gaussian as n→∞. [†] x is where it is centered.

You only get the Gaussian if you take the limit correctly.

In the visualization as you increase the number of bins, the Gaussian approximation becomes more and more squeezed, and by the weak law of large numbers the limit is a Dirac delta.

In order to get the Gaussian you'd need to be looking at a window whose width is proportional to the square root of the number of bins.

Re: The Central Limit Theorem Visualized with D3

#26
post #13

while i have the attention of HN, does anyone have suggestions on any other types of statistic visualizations?

I'd like to hear the answer to this as well. Especially in light of some of Bret Victor's recent talks, I'm very eager to hear about tools and visualizations that enhance thinking and learning.

Re: The Central Limit Theorem Visualized with D3

#27
post #22

Kind of a misleading animation, since n is the number of switches (4) and not the number of balls (which diverges to infinity). Setting the bins to 500 froze the browser, unfortunately. The physical machines that do this are undeniably cool, but especially when they have the curve painted on beforehand; this is the best I could find right now, but I remember seeing a pretty big one as part of a traveling mathematics…

what browser are you using? the bins tag has a max value set to 25

Re: The Central Limit Theorem Visualized with D3

#28
post #16

Earlier quoted context omitted.

Well, not really. The fact that CLT applies to a wide variety of distributions is a much stronger, mysterious and astonishing fact than what is demonstrated here. It would be like demonstrating that you've cracked RSA with p = 7, q = 11.

Agreed, learned more, was wrong, deleted comment. Curious though—doesn't the CLT apply to this distribution too, technically? Isn't the binomial distribution being sampled and converging on a normal distribution, as per the CLT? Maybe some more explanation would enlighten us.

Yes, this is definitely a special case of CLT.

For instance, see: https://en.wikipedia.org/wiki/De_Moivre%E2%80%93Laplace_theo...

Re: The Central Limit Theorem Visualized with D3

#30
post #22

Kind of a misleading animation, since n is the number of switches (4) and not the number of balls (which diverges to infinity). Setting the bins to 500 froze the browser, unfortunately. The physical machines that do this are undeniably cool, but especially when they have the curve painted on beforehand; this is the best I could find right now, but I remember seeing a pretty big one as part of a traveling mathematics…

When I worked at DEKA, I met a guy who designed and built an invertible Galton Box. The ball-holder was circular and if you spun it one way, the balls would fall into the expected bell curve. But if you turned it the other way, the pins would shift very subtly - so little you wouldn't really notice - but the balls would fall in a perfect inverse bell curve, with most of the balls on the outside and very few in the middle. I think the company helped him get a patent on the mechanism :)
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