The average rate of change is given by:
\[
\text{Average rate of change} = \frac{g(4) - g(-2)}{4 - (-2)} = \frac{3 - 6}{4 - (-2)} = \frac{-3}{6} = -0.5
\]
The average rate of change of \( g(x) \) over the interval \([-2, 4]\) is \(\boxed{-0.5}\).
The average rate of change of \( g(x) \) over the interval \([-2, 4]\) is \(\boxed{-0.5}\).