Correct

Correct. Do you see why? How is error variance
reduced with a within-subjects design? Think it
through. Error variance is that nonsystematic variance
that operates on individuals within a group. Because
error variance is random in its effects, it is as likely to
increase scores as it is to decrease scores. The major
contributor to error variance is individual differences--
those natural differences that exist from one individual to
another. When we use a within-subjects design (repeated
measures of the same participants in different experimental
conditions), we are not only reducing the number of different
individuals in the study, but are also using the same individuals
in each of the comparison groups. Thus, we have decreased
individual differences and, therefore, decreased error variance.