Standard Error: Okay, so I keep getting confused. If I have 2 samples from one treatment and 2 from another then I calc the difference between the means for these two samples, how do I find the standard error of the difference of the two means?

Question

trancenova · Answer

Does my question make sense?

anonymous · Answer

basically your looking for standard deviation?

trancenova · Answer

Well the standard error is the standard dev/ sqrt(n), but I presume any rules applying to stdev also apply for standard error.

anonymous · Answer

basically are you looking for a formula

trancenova · Answer

Hmmm if there is one? The problem is I can get the standard error of both means but when I minus one mean from the other I don't know the standard error of the resulting number

anonymous · Answer

there is a formula for this situation and i believe it can be applied here

anonymous · Answer

its a formula for a finding the standard deviation of the sampling mean differences

trancenova · Answer

Thanks, I'm looking it up now

trancenova · Answer

Just posting this so when I come looking for it again it'll be saved on here :P 

SE = sqrt[(s12/n1) + (s22/n2)]

where s1 is the standard deviation of sample 1,
 s2 is the standard deviation of sample 2, n1 is the size of sample 1, and n2 is the size of sample 2.

Cheers LagrangeSon, now my chart has error bars hehe  
P.s. You know there are 52 other facts you haven't read :P