forum 9: week of 12 March: Fisher and the design of experiments

Fragment of a discussion from Course talk:Phil440A
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This comment might be a little late but I just wanted to rephrase my question in because I am a notorious mumbler. The significance level corresponds to the probability that your results in a an experiment were obtained by chance (coin landed heads 5 times in a row) The P-value is the probability that your null hypothesis (This coin is unfair and obtains heads more often than tails) is true. Your results are significant if the P-value is less than the significance level. That would then mean that if there was a higher probability that your 5 coin flips were by chance than the probability that the coin was unfair your results would be significant in disproving the null hypothesis (that is was a faire coin). ...Well now that I've written it our it makes sense to me. I'll post this on the forum anyway in case anyone else had trouble. I was confused because i didn't understand that the goal was the disprove the null hypothesis and show that it was all due to chance instead.

18:46, 15 March 2012