Question

to test the effectiveness of a new treatment, a clinician measures cholesterol levels (in mg/dl) of 9 patients before and after treatment. the mean difference is 12, and the standard deviation of the differences is 6. what is the standard error for this test? 1 2 3 6

Explanation:

Step1: Recall the formula for standard error

The formula for the standard error ($SE$) of the mean difference in a paired - samples situation is $SE=\frac{s_d}{\sqrt{n}}$, where $s_d$ is the standard deviation of the differences and $n$ is the number of pairs.

Step2: Substitute the given values into the formula

We are given that $s_d = 6$ and $n=9$.
Substituting these values into the formula $SE=\frac{s_d}{\sqrt{n}}$, we get $SE=\frac{6}{\sqrt{9}}$.
Since $\sqrt{9}=3$, then $SE=\frac{6}{3}$.

Answer:

$2$