Reading 11 says for calculating value of t, when correlation is given - use the formula t= r (n-2) / (1+r^2)^1/2 for hyphothesis testing. Can someone help me explain, how they arrived at this formula. I just don’t seem to remember seeing this formula in L1 or I could have missed it?

Would you really like to see a derivation, or will you accept it if I tell you that the derivation won’t help you much and you are just going to have to learn the formula?

I have learnt the formula anyways, but was just wondering if it is something similar to those formulae that we studied at L1? I would not expect the complete derivation but atleast if you can give me an idea of how it came for, might help me remember this formula in a little easy way.

Amit This formula was there in L1 (at least when I studied for Dec 07). additionally - it should be (1-r^2) and not (1+r^2) as you have it. derivation of the formula is not a requirement. CP

yes you are right, it is 1-r^2. sorry for typo. Dec 07 had correlation/regression in L1 but it got removed from L1 in Jun 08. I remember studying some formulae for t,z,f in hypothesis testing but don’t think i ever read this. Thanks for the updates. I am going to have to just learn it.

ya gots ta do whats ya gots ta do playa.