I wouldn't know . I have two coins. One is yellow or white (fifa fair play coin). The other is Field Or Shield. One side has the field of play on it the other our RA shield logo.In my experience at least I've noticed that when asking 'heads or tails' pre-match about 7 or 8 out of 10 captains will call 'heads'.
I've no data to back this up just something I've noticed.
Anyone else come across this or am I suffering from confirmation bias?