Wednesday 11 April 2012

The improbable-ness of statistics

I have a statistics exam coming up soon and I just saw a video on probability so that is what I'm going to talk about today. (Side note: I don't think the link work - try searching on YouTube for Fun Science: Randomness by charlieissocoollike. Curse my lack of technological skills!) If I were to flip your average coin, there is not a 50:50 chance of getting heads. In part this is because of slight biases in flipping techniques (because there is a right and a wrong way to flip a coin!) and imperfections on the coin that make it more likely to land on one side. But even the probability of getting heads or tails is not necessarily 1. Okay, I'll admit that it is pretty likely that if you were to flip a coin a billion times, it's going to end up as one of those two outcomes. But there are other, admittedly highly unlikely, possibilities that could completely ruin any lovely heads/tails tree diagrams: - The coin could land on its side. This is actually not entirely out of the realms of plausibility. If you can balance a coin on its side without too much difficulty, then it could potentially land like that. What would you do then?! Call it a draw? Thump the table until it falls over (ruining the unbiased-ness of the already biased experiment). Probability: minute but still possible. - The coin might not land properly. Excluding the fact that it might land on its side, the coin still might not land in a recordable way. It might end up stuck in something. See that could happen. If you were to conduct the experiment in space, it might never land at all, just keep flipping around FOR ALL OF ETERNITY. By which point you would have given up and returned to Earth (unless you were really dedicated as a scientist). Probability: even less likely but still possible. - The coin might not make it. Imagine, if you will, that you had flipped that coin back in 2009 when the LHC was first started and everyone was panicked about the possibility of a blackfoot engulfing the Earth. Imagine (bear with me ere) that you flipped the coin inside the collider and a black hole appeared and swallowed your coin (and probably yourself and the rest of the planet too). It hasn't landed so you can't record a result, you can't do a retest and, like a school bully, the black hole has run off with your lunch money. Bit of a scientific nightmare. Probability: Admittedly a little unlikely but who knows? So basically, even when we think we have all the possible outcomes, we probably don't. And yes the probability of these outcomes are so minuscule we can probably safely ignore ten, they are still an option. And that is what I shall put on my test. ...And that'll probably be why I'll fail the test too!

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