Calculate the Difference Scores and Find M_D for the Following $$\begin{array} { r r r } \mathrm { A } & 12 & 14 \\\mathrm {~B} & 7 & 15 \\\mathrm { C } & 10 & 8 \\\mathrm { D } & 8 & 12\end{array}$$

Calculate the difference scores and find M_D for the following data from a repeated-measures study.Subject Treatment 1 Treatment 2 $$\begin{array} { r r r } \mathrm { A } & 12 & 14 \\\mathrm {~B} & 7 & 15 \\\mathrm { C } & 10 & 8 \\\mathrm { D } & 8 & 12\end{array}$$