You can load a die but you can't bias a coin (2002) [pdf] (opens in new tab)

If you go beyond the title and read the paper carefully, what it states is if you spin a coin rapidly in the air with a horizontal spinning axis and catch it in the air, then weighting the coin doesn't bias it. If you throw a coin in other ways (e.g. let it land on a surface), then you can of course bias a coin.

That's why cypherpunks each bring their own coin and XOR the heads. Or flip a biased coin twice. If you get HH or TT, discard and start over. If you get HT or TH, take the first flip of the pair.

More to the paper, I liked the point about using unexpected results to drive student engagement. In one of the early episodes of Very Bad Wizards, they described some aspects of teaching as like a magic show. I think it's a good analogy.

http://verybadwizards.com/

I still think you manufacture a (slightly) unfair coin: http://www.win-vector.com/blog/2015/04/i-still-think-you-can...

( The post got truncated by a bad character in my blockquote paste (sorry!). It should be legible now (and include two figures). )

This is only with solid coins. I'm pretty sure with a liquid centered coin, with sufficient tinkering, it would be possible to design a biased coin using the changing weight distribution to keep the flip biased to certain positions.

It's already biased towards the face that is facing up to start. With practice or by accident, you can toss it so that it wobbles but doesn't actually flip over. A casual observer cannot tell the difference.

Explained in http://www.amazon.com/Heads-Or-Tails-Gary-Kosnitzky/dp/B00FM...

This needs a 2002 in the title.

> The biased coin has long been part of statistical folklore, but it does not exist in the form in which it is imagined.

Sure it does, just abstractly. You can simulate a coin if any bias using a fair coin.

Got a lot of respect for Andrew Gelman, but it's too bad he didn't cite Persi Diaconis: http://statweb.stanford.edu/~susan/papers/headswithJ.pdf