Question: Develop a seasonally adjusted forecast model for order data. Forecast demand for each quarter for 2004 (using a linear trend line forecast estimate for orders in 2004). Develop a separate linear trend line forecast for each of the four seasons and forecast each season for 2004. Which of two approaches used appears to be more accurate. Use MAD to verify your selection.

ORDERS (1,000s)

Quarter 1999 2000 2001 2002 2003

Jan-Mar 18.6 18.1 22.4 23.2 24.5

Apr – Jun 23.5 24.7 28.8 27.6 31.0

Jul - Sep 20.4 19.5 21.0 24.4 23.7

Oct – Dec 41.9 46.3 45.5 47.1 52.8