A Comparative Psychologist Was Interested in the Effect of X-Irradiation $$\begin{array} { c c } \text { X-irradiated } & \text { Control } \\\hline 14 & 12 \\12 & 10 \\8 & 11 \\15 & 13 \\17 & 12\end{array}$$

Essay

A comparative psychologist was interested in the effect of X-irradiation on learning. A group of rats learned a simple maze and were paired on the basis of the number of errors. One group was X?irradiated; then both groups learned a new, more complicated maze, and errors were recorded.
a. Test for a difference between the two groups. Find the effect size index. Write a conclusion for the study. $$\begin{array} { c c } \text { X-irradiated } & \text { Control } \\\hline 14 & 12 \\12 & 10 \\8 & 11 \\15 & 13 \\17 & 12\end{array}$$
b. Identify the independent and dependent variables.