18. Revisit Example 9.27 and the power function graph in Figure 9.15 and consider the implications of the power function graph in the two dimensional parameter space

(m,s).

(a) Plot the power surface in three dimensions, the axes referring to power, the value of m, and the value of s.

(This is probably best done with the aid of a computer).

(b) Plot the isopower contour in the (m,s)-plane for a power level of .90. (An isopower contour is the set of

(m,s) points that result in the same level of power, which in the case at hand is equivalent to the set of

(m,s) points that result in the same value of the noncentrality parameter l). Interpret the isopower contour with respect to the ability of the test to detect deviations from the null hypothesis.