I need some clarifcation/help on a s2 question.
Method 1 H(0) p=0.5, H(1) p not= 0.5
n=20 x=7, test at 10% significance
So I thought:
X~B(20,0.5) under Ho
Ho: p = 0.5
H1: p doesn't = 0.5... See more
Test x=7
Reject Ho if P(x=<7)<0.05
Use tables to find out P(x<=7)=0.1316.
0.1316>0.05
therefore not significant, do not reject ho.
Method 2 But the book says this is not right, and my teacher says:
H0 : p=0.5
h1: p not= 0.5
x=7, 10% sig
X - B(20, 0.5)... See more
P(X<=7)+P(X>=13)=2P(X<=7) = 2x0.1316 = 0.2632
0.2632 > 10% so not significant
Which is right, I don't understand why the first method is wrong- why do you need to consider P(x>=13) even if it is a two tailed test?
Thank you.