Recent searches
Search options
What do we (a group of 50 scientists) and B. F. Skinner have in common? Of course winning an Ig Nobel prize! 
In a study led by František Bartoš where we performed 350,757 coin flips, we showed that when flipping a fair coin, it tends to land on the same side it started on (probability = 50.8%). Last week, we received the Ig Nobel prize for probability for this breath-taking finding. 
Links to paper and prize ceremony below
#CBDR flips coins
Read the paper here: https://arxiv.org/abs/2310.04153
Watch the Ig Nobel prize ceremony here: https://improbable.com/ig/archive/2024-ceremony/
arXiv.orgFair coins tend to land on the same side they started: Evidence from 350,757 flipsMany people have flipped coins but few have stopped to ponder the statistical and physical intricacies of the process. In a preregistered study we collected $350{,}757$ coin flips to test the counterintuitive prediction from a physics model of human coin tossing developed by Diaconis, Holmes, and Montgomery (DHM; 2007). The model asserts that when people flip an ordinary coin, it tends to land on the same side it started -- DHM estimated the probability of a same-side outcome to be about 51%. Our data lend strong support to this precise prediction: the coins landed on the same side more often than not, $\text{Pr}(\text{same side}) = 0.508$, 95% credible interval (CI) [$0.506$, $0.509$], $\text{BF}_{\text{same-side bias}} = 2359$. Furthermore, the data revealed considerable between-people variation in the degree of this same-side bias. Our data also confirmed the generic prediction that when people flip an ordinary coin -- with the initial side-up randomly determined -- it is equally likely to land heads or tails: $\text{Pr}(\text{heads}) = 0.500$, 95% CI [$0.498$, $0.502$], $\text{BF}_{\text{heads-tails bias}} = 0.182$. Furthermore, this lack of heads-tails bias does not appear to vary across coins. Additional exploratory analyses revealed that the within-people same-side bias decreased as more coins were flipped, an effect that is consistent with the possibility that practice makes people flip coins in a less wobbly fashion. Our data therefore provide strong evidence that when some (but not all) people flip a fair coin, it tends to land on the same side it started. Our data provide compelling statistical support for the DHM physics model of coin tossing.
@aaronlob Congratulations :-)