${\overline{X}}_{d}=\text{\hspace{0.17em}}±t\text{\hspace{0.17em}}\frac{{s}_{d}}{\sqrt{n}}$

Description:

Math equation. For less than 30 pairs, use the t-table. The confidence interval for the difference is the difference plus or minus t times the standard deviation of the difference divided by the square root of the sample size.