Improbable Probability and Why I Don't Trust Math

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Improbable Probability and Why I Don't Trust Math

Postby Proofrdr » 10 Jun 2013, 03:58

The situation:
Two toothbrush tips sit in a small cup, brush up and not-visible identifying color bands, red and blue, down. Twice a day, without seeing the bands, I reach for one, hoping it's the red one.

The probability:
Given 2 items and a random draw, the probability of getting either brush is 50% on every draw.

What fate really does to me day after day:
In a month [30 days] of recorded brush grabs, I selected my own brush tip only 3 times in the morning, and impossibly, ridiculously, insanely, only 1 time at night. How can this be? What good is probability if real results are so improbable?
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Re: Improbable Probability and Why I Don't Trust Math

Postby ElaineB » 10 Jun 2013, 06:30

lol
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Re: Improbable Probability and Why I Don't Trust Math

Postby Proofrdr » 10 Jun 2013, 07:37

You laugh, but such things confound and befuddle me! :thinking:
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Re: Improbable Probability and Why I Don't Trust Math

Postby Baker » 10 Jun 2013, 07:52

Probablility is just that, Proof. There is always the chance that unlikely sequences of events will happen. BTW I love that you kept track for a month. :-)
Those who can make you believe absurdities can make you commit atrocities ~ Voltaire
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Re: Improbable Probability and Why I Don't Trust Math

Postby Proofrdr » 10 Jun 2013, 08:21

I understand "unlikely sequences of events." What comprises an acceptable unlikely sequence--that's what drove me to track it. In late March, I became one-handed/left-handed. Everything requiring a hand became a special effort. Anything that interrupted an activity became an annoyance. It was then I noticed how frequently I kept having to change the damned brush I'd picked from the cup. Then, when I went an entire week selecting the wrong one, morning and night, I decided to track it.

I'm like a dog on a bone when something perplexes me. Plus, I'm retired and looking for meaningful activity. ;)

I still think the Tooth Fairy is involved.
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Re: Improbable Probability and Why I Don't Trust Math

Postby Kurna » 10 Jun 2013, 12:30

Interesting. :thinking:

But it also brings up the question, if the draw is really completely random. Maybe either/both of you tend to go (subconsciously) more for one side than the other. Depending on handedness, order in which you usually use them, how often the cup is moved, where exactly it is positioned, etc. there might be a bias for the wrong brush.

E.g. (simplyfied - cup is never moved, it's always person A - person B - person A - person B etc.) most people would probably (if it's done subconsciously) rather pick up the right brush with the right hand (or the left brush with the left hand - depending on the handedness), since it's the one slightly closer. As this leaves slightly more space on that side, they will also put it back there. But if B has the same handedness as A, she will exchange your brush with hers on her turn. And therefore from then on both would always pick up the wrong one first.

In reality it would be much more complicated of course (I already mentioned some possible influences). But I wouldn't be surprised, if it is actually not as completely random as one may assume at first.

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Re: Improbable Probability and Why I Don't Trust Math

Postby FranW » 12 May 2014, 07:21

Sort of on the same subject: Spurious Correlations. This, I think, will be a great teaching tool for me to use for baby students!

See 'em all here: http://www.tylervigen.com/

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Re: Improbable Probability and Why I Don't Trust Math

Postby Baker » 12 May 2014, 07:28

lol Nic drowned them all!
Those who can make you believe absurdities can make you commit atrocities ~ Voltaire
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Re: Improbable Probability and Why I Don't Trust Math

Postby Proofrdr » 12 May 2014, 10:12

Those are really cool. I liked the correlation between the per capita consumption of margarine in the US with the divorce rate in Maine.
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Re: Improbable Probability and Why I Don't Trust Math

Postby wildlx » 14 May 2014, 04:14

lol
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