How to flip a coin

Chris Blattman reports:

Using a high-speed camera that photographed people flipping coins,
the three researchers determined that a coin is more likely to land
facing the same side on which it started. If tails is facing up when
the coin is perched on your thumb, it is more likely to land tails up.

How much more likely? At least 51 percent of the time, the
researchers claim, and possibly as much as 55 percent to 60 percent –
depending on the flipping motion of the individual.

The original research is here.