Men det är bara så enkelt som att du kan singla en slant hur länge som helst och du kommer alltid få krona, P(A)=0.5 eller klave, P(B)=0.5.
Kan ju komma på högkant oxo? om inte annat:
Coin-tossing research
General status of the research on coin toss:
“Their preliminary data suggest that a coin will land the same way it started about 51 percent of the time. It would take about 10,000 tosses before a casual observer would become aware of such a small bias, Diaconis says. "Maybe that's why society hasn't noticed this before," he says.
This slight bias pales when compared with that of spinning a coin on its edge. A spinning penny will land as tails about 80 percent of the time, Diaconis says, because the extra material on the head side shifts the center of mass slightly.”
Diaconis quoted in Science News
http://www.sciencenews.org/articles/20040228/fob2.asp
More about Diaconis and his experiment:
http://news-service.stanford.edu/news/2004/june9/diaconis-69.html
http://www.npr.org/templates/story/story.php?storyId=1697475
Previous work:
http://www.sciencenews.org/articles/20040228/mathtrek.asp
About the penny:
http://www.sciencenewsforkids.org/pages/puzzlezone/muse/muse0403.asp
Bias catching or letting fall on table:
“Experimental data suggest that a well-tossed fair coin is a satisfactory randomizer for achieving an equal balance between two possible outcomes. However, this equity of outcome doesn't necessarily apply to a coin that rolls along the ground or across a table after a toss. An uneven distribution of mass between the two sides of a coin and the nature of its edge can slightly bias the outcome to favor, say, heads over tails.
The U.S. penny -- with Abraham Lincoln's head on one side and the Lincoln Memorial on the other -- provides a striking example of such a bias. Stand a dozen or so pennies on edge on the surface of a table. Then bang the table so that the pennies topple over. You'll find that nearly always more heads than tails are face up. Sometimes all the coins end up heads. On the other hand, spinning pennies tend to land with tails up more often than heads!”
http://www.sciencenews.org/pages/sn_arc97/12_13_97/mathland.htm
Spin, flip, tilt and previous work:
There are three kinds of coin experiments that are often carried out in an introductory statistics course using U.S. pennies. Following terminology of Robin Lock we shall call them flips, tips and spins. For a "flip experiment" you toss coins in the air so that they flip over a number of times and you either catch them or let them fall on a surface where they will not bounce, For a "tip experiment" you stand a number of coins on their edge on a table and strike the table gently until all the coins have fallen over. For a "spin experiment" you spin coins on a table counting only those that comes to rest on the table without having hit any other object. . Conventional wisdom is that a flip experiment should not result in significantly more heads or tails than could be accounted for by chance. A tilt experiment should result in significantly more tails than heads and a spin experiment significantly more tails than could be accounted for by chance.
As we remarked in Chance News 10.03 there have historically been some large flip experiments. Here are the results of three such experiments.
Number of trials Number of heads Proportion of heads Standard deviations from mean for fair coin 95% Confidence interval for proportion of heads
Buffon 4,040 2,048 .5070 .881 (.491, .522)
Pearson 24,000 12,012 .5005 .155 (.494, .507)
Kerrich 10,000 5,067 .5067 1.34 (.477, .517)