An Experimental Neuropsychologist Wishes to Determine Whether a New Drug

Multiple Choice

An experimental neuropsychologist wishes to determine whether a new drug (X-9) enhances the growth of new, functional brain tissue after maximal brain growth has already been attained after a period of 1 month and 6 months. Five rats were run in a series of three different mazes. All of the mazes were judged to be of equal difficulty. The time in seconds to solve each maze is recorded for each rat across its three mazes. X-9 was given 2 weeks before testing. A prior study statistically demonstrated that rats not given X-9 did not improve their times. Is there any evidence X-9 works? $\begin{array} { l c c c c c c } \hline & { \text { 1 Month } } & & & \text { 6 Months } \\\hline & \text { Trial 1 } & \text { Trial 2 } & \text { Trial 3 } & \text { Trial 1 } & \text { Trial 2 } & \text { Trial 3 } \\\hline \text { Rat 1 } & 10 & 12 & 5 & 4 & 5 & 4 \\\text { Rat 2 } & 15 & 14 & 8 & 6 & 5 & 4 \\\text { Rat 3 } & 14 & 14 & 7 & 6 & 7 & 7 \\\text { Rat 4 } & 9 & 10 & 5 & 7 & 8 & 8 \\\text { Rat 5 } & 12 & 11 & 4 & 7 & 6 & 7 \\\hline\end{array}$
-The df for the trials main effect is

A) 1
B) 2
C) 3
D) 24
E) 29