1-tail vs 2 tail t-test

CFA Level II
#1

Hey guys, I am still confused as to when do we use 1-tail and when do we use 2-tail t-test? Cheers

#2

Use a 1-tail test when H0: parameter ≥ value, Ha: parameter < value.

Use a 1-tail test when H0: parameter ≤ value, Ha: parameter > value.

Use a 2-tail test when H0: parameter = value, Ha: parameter ≠ value.

#3

Yeah, what he said!

#4

Thanks guys, good luck on Sat