The cross section data for 50 states and Washington D.C. for mortality rates and their determinants. The Y variable is MORT (Total Mortality rate per 100,000 population).

The explanatory variables are:

INCC = per capita income by state in dollars

POV = proportion of families living below the poverty level

EDU1 = proportion of population completing four years of high school.EDU2 = proportion of population completing four years or more of college.

ALCC = Per-capita consumption of alcohol in gallons.

TOBC = per-capita consumption of cigarettes in packs.

HEXC = healthcare expenditures per capita in $.PHYS= physicians per 100,000 population.

URB = proportion of population living in urban areas.

AGED = Proportion of population over the age of 65.

a) For each explanatory variable, explain why it might have a causal effect on mortality (explain why it is + or -).

d) What other variables can you think of that might be an explanatory variable in the model?