Forecast the advertising revenue for each quarter in 2011 using seasonal dummy variables and a best subsets regression then calculate the MAD for the forecast. (Let the first dummy variable be equal to 1 for Quarter 2, and so on, following the order of the seasonal categories in the given table.) Interpret the meaning of the coefficients for the seasonal dummy variables.

2008 Quarter Revenue ($ millions) 1 540 2 516 3 488 4 500 2009 Quarter Revenue ($ millions) 1 433 2 407 3 402 4 460 2010 Quarter Revenue ($ millions) 1 347 2 297 3 292 4 332 2008 Quarter Revenue ($ millions) 1 540 2 516 3 488 4 500 2009 Quarter Revenue ($ millions) 1 433 2 407 3 402 4 460 2010 Quarter Revenue ($ millions) 1 347 2 297 3 292 4 332