# Thread: I need a few equations that I can't find...

1. ## I need a few equations that I can't find...

Hi
Just wanted to ask people if they could help me find a few equations I am looking for; I am revising for a test and the teacher said that a few of these may come up, so you must remember them. However, I can't find these particular formulae, so I was wondering if anyone could point me in the right direction or just help me!

I cant find: the unbiased estimator of population variance- is this just sample variance?
The equation for linear combination of variables: mean and the one for variance

and finally, the test statistic for hypothesis test, beta=o and the test statistic for population proportion. I would be really grateful if someone either knew these formulae or knows where I could find them...

Thanks

2. ## Re: I need a few equations that I can't find...

the sample variance, with the n-1 in the demoninator is unbiased for $\displaystyle \sigma^2$
That's why the n-1 is there.

3. ## Re: I need a few equations that I can't find...

I don't know what you mean by
'The equation for linear combination of variables: mean and the one for variance'

and as for beta=0, it seems you're doing regression
SO I clearly need to know the model that you are proposing.
Most likely it's simple linear regression.