Probability of rock-paper-scissors

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TuxDave

Lifer
Oct 8, 2002
10,571
3
71
Players tend to pick Scissors first,

SHHHHHHHH!!!! Don't let this secret out. I once wanted to prove this to my friend back in high school so during lunch time I played a single match with 5-6 different people (none of them saw the previous matches) and beat them all with rock.
 

DrPizza

Administrator Elite Member Goat Whisperer
Mar 5, 2001
49,601
166
111
www.slatebrookfarm.com
Interestingly, even if it is possible to improve your chances of winnng beyond 50% by using a strategy, this is completely nullified if the person you are playing against is in fact making their choices completely randomly. It is only possible to have a meaningful strategy if the other person is also using some non-random choice strategy.

There is no strategy to beat random...!

Most humans are incapable of doing this randomly. Hell, you could simplify it to just two choices - heads and tails. Have a human "randomly" write down a sequence of 50 heads/tails. Do 10 trials. Then, do 10 trials where you actually flip a coin in a real, random way, and record 10 trials of 50 flips each.

Mix the results of those 20 trials all together and someone good with statistics will be able to identify the 10 human generated "random" sequences, generally quite simply.
 

TecHNooB

Diamond Member
Sep 10, 2005
7,458
1
76
Most humans are incapable of doing this randomly. Hell, you could simplify it to just two choices - heads and tails. Have a human "randomly" write down a sequence of 50 heads/tails. Do 10 trials. Then, do 10 trials where you actually flip a coin in a real, random way, and record 10 trials of 50 flips each.

Mix the results of those 20 trials all together and someone good with statistics will be able to identify the 10 human generated "random" sequences, generally quite simply.

lies!
 

eLiu

Diamond Member
Jun 4, 2001
6,407
1
0

haha truths!

If you have access to a college library that keeps its old (from the 50-60s or earlier) books, you can find gigantic volumes of tabulated random numbers.

Before you could call rand(), this is where scientists/engineers/statisticians/etc. went for their random number needs. It was well-recognized that you couldn't just have a human choose them. I have no idea how the books were compiled nor whether their randomness was good, but I would guess that a room full of asian kids executed some large-period PRNG algorithm until they passed out, lol.
 

TecHNooB

Diamond Member
Sep 10, 2005
7,458
1
76
haha truths!

If you have access to a college library that keeps its old (from the 50-60s or earlier) books, you can find gigantic volumes of tabulated random numbers.

Before you could call rand(), this is where scientists/engineers/statisticians/etc. went for their random number needs. It was well-recognized that you couldn't just have a human choose them. I have no idea how the books were compiled nor whether their randomness was good, but I would guess that a room full of asian kids executed some large-period PRNG algorithm until they passed out, lol.

i was just nitpicking the word random
 

iCyborg

Golden Member
Aug 8, 2008
1,330
56
91
Most humans are incapable of doing this randomly. Hell, you could simplify it to just two choices - heads and tails. Have a human "randomly" write down a sequence of 50 heads/tails. Do 10 trials. Then, do 10 trials where you actually flip a coin in a real, random way, and record 10 trials of 50 flips each.

Mix the results of those 20 trials all together and someone good with statistics will be able to identify the 10 human generated "random" sequences, generally quite simply.
There's a story about a professor who asked students to generate a sequence of 200 elements, each 0 or 1. They could either generate it by a computer or by hand. He correctly guessed which method was used in all cases. And the criteria he used was very simple: there's a high probability that there will be at least one sequence of six 0s or 1s. Human generated sequences never had them

Yep, humans are poor at producing random numbers. E.g. there's a law that says that a random integer (with no fixed upper limit) will start with digit 1 in 30.1% of the cases, a lot of natural data exhibits this law, called Benford's law. I heard IRS uses it to detect possible tax fraud.
 

Ninjahedge

Diamond Member
Mar 2, 2005
4,149
1
91
I was thinking about that, the heads-tails thing.

i think just to be annoying I would have done runs with no real pattern....

HHHHTTHTHHHTTTTTHTHHHHHHHTTHTHHHHTTTTTT....... That 6 in a row thing is an easy one to see if you KNOW what you are doing... Me? I was just thinking of being faceteous.....
 
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