QUESTION $17$

Demand for a product and the forecasting department$$s forecast $($na$$ve model$)$ for a product are shown below. Compute the mean squared error.

$$

Period

Actual Demand

Forecasted Demand

$1$

$12$

$--$

$2$

$15$

$12$

$3$

$14$

$15$

$4$

$18$

$16$

a$.$

$5\mathrm{.}33$

b$.$

$3\mathrm{.}33$

c$.$

$4\mathrm{.}67$

d$.$

$6\mathrm{.}67$