C'est en anglais mais cette étude est ... intéressante?
http://www.awesomedice.com/blog/353/d20-dice-randomness-test-chessex-vs-gamescience/Methodology
For the principle test we used one Chessex d20 and one GameScience d20, both brand new right out of the packaging. The GameScience d20 was inked with a Sharpe to make it easier to read the results, but the dice were not modified in any other way.
The dice were rolled by hand on a battlemat on a level table. For this experiment the dice were rolled on the surface for at least two feet and had to bounce off a flat backstop before coming to rest. This is similar to the requirements of craps tables in casinos. Our logic is that if this method successfully prevents cheating with six-sided dice, it will more than suffice for d20 dice being rolled without any intent to alter the results. (Since casinos are not losing money on gambling, we assume they know what they’re doing).
Each die was rolled 10,000 times, and the results recorded.
Test Results
After an insane amount of dice rolling, here is a quick look at the results for each die