The following data shows the number of passenger enplanements at Laguardia Airport in New York.

Year Enplanements

$($in thousands$)$

$200922,142$

$201023,983$

$201124,122$

$201225,708$

$201326,722$

$201426,955$

$201528,438$

$201629,786$

$201729,502$

The airport authority would like to predict the number of passenger enplanements in the future.

Below, you are going to:

Use $2014-2017$ as a hold out sample. Calculate the initial Level and Trend using all the data from $2009-2013.$ Utilize

these as the starting point for updating based on seeing $2009$ and carry it forward. That is$,$ use the calculated Level and

Trend as period $0$ and start your first update with the $2009$ data.

Use Holt's method $($alpha$=0\mathrm{.}1,0\mathrm{.}25$; beta$=0\mathrm{.}1,0\mathrm{.}25,$ total of four combinations$)$ to forecast the demand for the hold out

sample.

Calculate the RMSE $($square root of MSE$),$ MAD, and TS for each

What is the initial Level?

What is the updated level in $2009?$