Answer
1. The deviation score
2. The minimum
Work Step by Step
1.if the mean of a distribution is subtracted from each score in that distribution and the differences are added, the sum will be zero ($\sum_{}^{}(X-\bar{X})=0$. This is the deviation score.
2. $\sum_{}^{}(X-\bar{X})^{2}$ is a minimum because If we subtract the mean from each score, square each deviation, and add the squared deviations together, the resulting sum will be smaller than if any number other than the mean had been used.
(p. 43)
