The file P11_62.xlsx has (somewhat old) data on several countries. The variables are listed here.
• Country: name of country
• GNPCapita: GNP per capita
• PopGrowth: average annual percentage change in population, 1980–1990
• Calorie: daily per capita calorie content of food used for domestic consumption
• LifeExp: average life expectancy of newborn given current mortality conditions
• Fertility: births per woman given current fertility rates
With data such as these, cause and effect are difficult to determine. For example, does low LifeExp cause GNPCapita to be low, or vice versa? Therefore, the purpose of this problem is to experiment with the following sets of dependent and explanatory variables. In each case, look at scatterplots (and use economic reasoning) to find and estimate the best form of the equation, using only linear and logarithmic variables. Then interpret precisely what each equation is saying.
a. Dependent: LifeExp; Explanatories: Calorie, Fertility
b. Dependent: LifeExp; Explanatories: GNPCapita, PopGrowth
c. Dependent: GNPCapita; Explanatories: PopGrowth, Calorie, Fertility