# How does power analysis differ between paired sample and independent groups t-test?

Suppose in group 1 there are $n$ people and in group 2 there are $n$ people. If we conduct a 2 sample t test versus a paired t test, would we use $2n$ for power calculations in the two sample t test and $n$ as the sample size for the paired t test?

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The OP may wish to see my answer to a very similar question here: stats.stackexchange.com/questions/71525/… –  Jake Westfall Oct 1 '13 at 1:29

In general, the way that input is specified depends somewhat on the equations or software that you use to calculate the statistical power. But yes, it would be normal to specify the sample size in paired-samples t-test as the sample size $n$, and for independent groups t-test it would be the sum of the two group sample sizes, which when equal would be $2n$.