## TranceNova 4 years ago 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?

1. TranceNova

Does my question make sense?

2. LagrangeSon678

basically your looking for standard deviation?

3. TranceNova

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

4. LagrangeSon678

basically are you looking for a formula

5. TranceNova

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

6. LagrangeSon678

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

7. LagrangeSon678

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

8. TranceNova

Thanks, I'm looking it up now

9. TranceNova

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