Can I really decide on my own that "the probability of being right is only 3%, so it's wrong!" Can I decide on my own that it is wrong because the probability of being right is only 3%?
Of course not. In statistical hypothesis testing, this criterion is named the significance level α and is determined before any calculations are made. Usually, 5% or 1% (α = 0.05 or a = 0.01) is used. In this case, if the significance level is 5%, H0 can be judged to be wrong. However, if the significance level is 1%, H0 cannot be wrong.
