ST590G -- FALL 2012 
     
     Class Exercise #1 -- due Thursday, 23 August 2012

     Our Group ___________________________________________________

     The files are in 'aug12' directory.

     In the file CPIAUNS.txt are values of the Consumer Price Index 
     for all urban consumers, not seasonally adjusted, from 1913 to 
     the present.  This file is tab-delimited, with multiple header 
     lines.  After the header, the date is given as yyyy-mm-01 and 
     the value of the price index.  (Data obtained from St. Louis 
     Fed's FRED database.)

     a) Print out the first few and last few observations.

     b) Create a dataset with variables YEAR, MONTH, a SAS date
     variable corresponding to the 15th of the month, the CPI and 
     its first difference (value - previous month's value).
     (Hint: either lag() or retain.)


     In the file spot_num.txt are monthly sunspot numbers from
     1749 to the present.  (The source is the NASA website:
        http://solarscience.msfc.nasa.gov/SunspotCycle.shtml )
     Here also is a header line, and then columns corresponding
     to YEAR, MONTH, SSN (Sunspot Number), and DEV (standard 
     deviation)(SSN is monthly summary of daily values.)

     c) Create a dataset with variables YEAR, MONTH, a SAS date
     variable corresponding to the 15th of the month, SSN and DEV.

     d) Merge the two datasets and delete observations where one
     or the other is missing.

     e) Plot first differences vs time.
     f) Plot SSN vs time.
     g) Plot first differences vs SSN.  Also compute the
     correlation between the two.
     h) Plot SSN and DEV.  We sometimes think that the variance
     might be related to the mean.  Do you see any relationship?

     
     ** Email results to monahan@ncsu.edu and include
      (1) List group members (and make sure you copy them on the email)
      (2) Your code * With as many comments as you have toes! *
      (3)  Your output
      (4)  The answers to any questions asked.