An analyst must decide between two different forecasting techniques for weekly sales of inline skates: a linear trend equation and the na$$ve approach. The linear trend equation is yt $=124+2$t$,$ and it was developed using data from periods $1$ through $10.$

Requirements: Based on data for periods $11$ through $19$ as shown below, show which of the forecasting technique has greater accuracy?

a$)$Perform demand forecast for periods $1219$ using the na$$ve method.

b$)$Perform demand forecast for periods $1119$ using the given linear trend equation.

c$)$ Compute MAD $($mean absolute deviation$)$ and determine which forecast technique is better. Period $($t$)$

Units sold

$11$

$147$

$12$

$148$

$13$

$151$

$14$

$145$

$15$

$155$

$16$

$152$

$17$

$155$

$18$

$157$

$19$

$160$