@ U.S. Presidential Approval data, collected by Neal Beck, UCSD. In the ascii 
file, all but Ronald Reagan's term is presently commented out.  This enables 
one, for pedagogical purposes, to ignore the issue regarding the effect of the 
approval of a president in his last month on the approval of the next president 
in his first month.

year = year
month = 1,...12
dinfl = change in inflation
dunem = change in unemployment
infl = inflation
app  = presidential approval in percentage
unem = percent unemployed
vietnam = battle deaths during vietnam in 10K's.
watergt = dummy variable
  last 2 vars are constants during Reagan's term.
@
input approval.asc;
output approval;
invar year month dinfl dunem infl app unem vietnam watergt;