Table 18,19 shows a portion o f data on net private housing units sold (in 1,000s), and real per-capita gross domestic product (in $ 1,000s); the entire data set is on the text website, labeled Housing Units. Let Housing denote housing units sold and GDP denote real per-capita gross domestic product. Estimate the following three models and use the most suitable model to make a forecast for housing units sold in 2009.

Model 1: Housingt = ß0 + ß1GDPt-1 + єt.

Model 2: Housing, = ß0 + ß1 Housingt-1 + єt .

Model 3: Housing, = ß0 + ß1GDPt-1 + ß2 Housingt-1 + єt