_version_ 1866912430356955136
author Bartoš, František
Sarafoglou, Alexandra
Godmann, Henrik R.
Sahrani, Amir
Leunk, David Klein
Gui, Pierre Y.
Voss, David
Ullah, Kaleem
Zoubek, Malte J.
Nippold, Franziska
Aust, Frederik
Vieira, Felipe F.
Islam, Chris-Gabriel
Zoubek, Anton J.
Shabani, Sara
Petter, Jonas
Roos, Ingeborg B.
Finnemann, Adam
Lob, Aaron B.
Hoffstadt, Madlen F.
Nak, Jason
de Ron, Jill
Derks, Koen
Huth, Karoline
Terpstra, Sjoerd
Bastelica, Thomas
Matetovici, Magda
Ott, Vincent L.
Zetea, Andreea S.
Karnbach, Katharina
Donzallaz, Michelle C.
John, Arne
Moore, Roy M.
Assion, Franziska
van Bork, Riet
Leidinger, Theresa E.
Zhao, Xiaochang
Motaghi, Adrian Karami
Pan, Ting
Armstrong, Hannah
Peng, Tianqi
Bialas, Mara
Pang, Joyce Y. -C.
Fu, Bohan
Yang, Shujun
Lin, Xiaoyi
Sleiffer, Dana
Bognar, Miklos
Aczel, Balazs
Wagenmakers, Eric-Jan
author_facet Bartoš, František
Sarafoglou, Alexandra
Godmann, Henrik R.
Sahrani, Amir
Leunk, David Klein
Gui, Pierre Y.
Voss, David
Ullah, Kaleem
Zoubek, Malte J.
Nippold, Franziska
Aust, Frederik
Vieira, Felipe F.
Islam, Chris-Gabriel
Zoubek, Anton J.
Shabani, Sara
Petter, Jonas
Roos, Ingeborg B.
Finnemann, Adam
Lob, Aaron B.
Hoffstadt, Madlen F.
Nak, Jason
de Ron, Jill
Derks, Koen
Huth, Karoline
Terpstra, Sjoerd
Bastelica, Thomas
Matetovici, Magda
Ott, Vincent L.
Zetea, Andreea S.
Karnbach, Katharina
Donzallaz, Michelle C.
John, Arne
Moore, Roy M.
Assion, Franziska
van Bork, Riet
Leidinger, Theresa E.
Zhao, Xiaochang
Motaghi, Adrian Karami
Pan, Ting
Armstrong, Hannah
Peng, Tianqi
Bialas, Mara
Pang, Joyce Y. -C.
Fu, Bohan
Yang, Shujun
Lin, Xiaoyi
Sleiffer, Dana
Bognar, Miklos
Aczel, Balazs
Wagenmakers, Eric-Jan
contents Many people have flipped coins but few have stopped to ponder the statistical and physical intricacies of the process. 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 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.
format Preprint
id arxiv_https___arxiv_org_abs_2310_04153
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Fair coins tend to land on the same side they started: Evidence from 350,757 flips
Bartoš, František
Sarafoglou, Alexandra
Godmann, Henrik R.
Sahrani, Amir
Leunk, David Klein
Gui, Pierre Y.
Voss, David
Ullah, Kaleem
Zoubek, Malte J.
Nippold, Franziska
Aust, Frederik
Vieira, Felipe F.
Islam, Chris-Gabriel
Zoubek, Anton J.
Shabani, Sara
Petter, Jonas
Roos, Ingeborg B.
Finnemann, Adam
Lob, Aaron B.
Hoffstadt, Madlen F.
Nak, Jason
de Ron, Jill
Derks, Koen
Huth, Karoline
Terpstra, Sjoerd
Bastelica, Thomas
Matetovici, Magda
Ott, Vincent L.
Zetea, Andreea S.
Karnbach, Katharina
Donzallaz, Michelle C.
John, Arne
Moore, Roy M.
Assion, Franziska
van Bork, Riet
Leidinger, Theresa E.
Zhao, Xiaochang
Motaghi, Adrian Karami
Pan, Ting
Armstrong, Hannah
Peng, Tianqi
Bialas, Mara
Pang, Joyce Y. -C.
Fu, Bohan
Yang, Shujun
Lin, Xiaoyi
Sleiffer, Dana
Bognar, Miklos
Aczel, Balazs
Wagenmakers, Eric-Jan
History and Overview
Data Analysis, Statistics and Probability
Other Statistics
Many people have flipped coins but few have stopped to ponder the statistical and physical intricacies of the process. 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 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.
title Fair coins tend to land on the same side they started: Evidence from 350,757 flips
topic History and Overview
Data Analysis, Statistics and Probability
Other Statistics
url https://arxiv.org/abs/2310.04153