[Vecr]

That's not the problem. You can test that by using a highly secure random number generator, e.g. /dev/random in Linux, to select the initial side. Keep track of that initial side, record the side it lands on. This paper shows a same-side bias, not a heads bias.

[japoco]

A same side bias is either a heads bias or a tails bias.

[Vecr]

How? I described how to randomize the initial side. Boolean true for heads, boolean false for tails, for example. Keep pulling those from the Kernel's secure RNG.

[alt227]

Its not, its a bias towards which side the coin started on.

[japoco]

Which is either heads or tails.

[glxxyz]

A coin with a heads bias is more likely to land on heads no matter how it's thrown.

A coin with a same side bias is more likely to land on heads if it's thrown with heads facing up, and more likely to land on tails if thrown with with tails facing up.

[toast0]

If you take a specific coin and find that when you prepare it to be flipped showing heads up, that it is more likely to land heads up, and that when you prepare it to be flipped tails up, it is more likely to land tails up, it seems confusing to call that coin 'heads or tails biased'