1. Download these four datasets: jng1.dta Download jng1.dta(ages of individuals in a group), jng2.dta Download jng2.dta(gender of those same individuals), jng3.dta Download jng3.dta(two years of residence location for again the same group), and jng4.dta Download jng4.dta(age information for another group of individuals).
   • Merge the first three. After the merge, you should have two years of annual state of residence data for four individuals.
   • Assume that the age variable is for 2010. Now we have an error in the data, as people would have been a year older in 2011. Try replacing the ages to reflect this.
   • Question (a): What is the average age of individuals in the sample during 2011? How about during 2012?
   • Question (b): What are the standard deviations (SD) of ages during 2010 and 2011?
   • Question (c): For your answer to part (b) above, How different are the two SDs? Do you find this to be surprising? Why or why not?