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 forcast 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

$11147$

$12148$

$13151$

$14145$

$15155$

$16152$

$17155$

$18157$

$19160$