Quadratic trend model
Fit a quadratic trend model to the data and write down its forecasting equation (expressing each coefficient to 2 d.p.'s). USA quarterly Industrial Production Index from Q1 1998 to Q4 2005 2002=100, Seasonally Adjusted, Source: US Federal Reserve Board 2001Q1 136.7 2001Q2 124.1 2001Q3 120.5 2001Q4 117.4 2002Q1 101.1