# Significance Levels(Region of rejection) vs P value comparison

Correct me if I am wrong, The region of rejection is we picked up a significant level then use that to calculate rejection region while P value is the conditional probability of alternative hypothesis $Ha$ on $Ho$ is true then we compare with significant level?

Is significant level a conditional probability of Reject Ho on Ho is true?

• $p$-value has nothing to do with $H_0$ being true. Check stats.stackexchange.com/questions/31/… for a start or this recent thread stats.stackexchange.com/questions/347653/…
– Tim
May 24, 2018 at 11:58
• Thanks. According to the link you refer, $P$($Samplemean$ ≥ 5ft 9inches|$Truevalue$=5ft7inches).Which the true value is $Ho$ is true which $u$ is population mean? I thought it is same as my understanding? May 24, 2018 at 12:33
• $P(X|H_0) \ne P(H_0|X)$
– Tim
May 24, 2018 at 12:34
• Thanks Tim. If I edit my question as this way, does it make more sense? May 24, 2018 at 12:42
• re-read/digest the link, my understanding is: region of rejection is by positioning $Z$ test result in the confidence interval, we can see whether the null hypothesis is rejected or not. Same conclusion can be obtained from $P$ value test. After calculate $P$ value from alternativehy pothesis $Ha$ on Null hypothesis $Ho$, if value is greater than significant level then we don't reject $Ho$, but if value is smaller, we reject it. May 24, 2018 at 13:13