The Journal of World-Systems Research (Summer 2003) reported on a study of

The Journal of World-Systems Research (Summer 2003) reported on a study of the link between foreign investments made 16 years earlier and carbon dioxide emissions. The researchers modeled the annual level (y) of CO2 emissions as a function of seven independent variables for n = 66 developing countries. A matrix given the correlation (r) for each pair of independent variables is shown at the bottom of the page. Identify the independent variables that are highly correlated. What problems may result from including these highly correlated variables in the regression model?