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S2 hypothesis testing

Why do we halve the significance level in 2 tail testing?
Original post by uchihaitachi0023
Why do we halve the significance level in 2 tail testing?


At the 5% significance level, the probability of being “in the tail” is 5%. This can be a single 5% tail or an upper and lower tail of 2.5% each. The total probability has to be 5% in both cases.

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