What Is The General Formula Used For Calculating The Standard Error Of Two Means?

Asked By Joseph M Helms 0 points N/A Posted on - 10/31/2017

I’ve come across two formulas while searching for calculating the estimate of the standard error of two means:

As these are two different formulas, in what way are they considered as the same?

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Answered By Garrett Shinault 0 points N/A #305592

What Is The General Formula Used For Calculating The Standard Error Of Two Means?

In both scenarios σ 1 and σ2 are unknown. The second formula uses the assumption that σ1 is equal to σ2, and is trying to estimate the shared variance obtained by combining all the observations, and is calculating a weighted mean.

Thus, the cause on the left plays the role of both s12 and s22 in the second equation. This method can be used when you have small sample sizes, and the equal variance assumption is valid. Hence both are the formulas for the standard error of two means but in different cases.

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• Posted on - 10/31/2017
• Question Category: Others