/* In this data set, we combined fall enrollment data   */
/* from 1990 to 2003 to track student histories over time  */
/* The file names should be simplified so we can say:    */
/* merge fall1990-fall2003, but this file was built      */
/* sequentially.  The data contained numerous missing    */
/* values since students are only enrolled for 1-6 years */ 
data uscmerge;
merge fall90 fall91 fall92 fall93 fall94 fall95 fall96
      fall97 fall98 fall98 fall99 fall2000 fall2001
	  fall2002 fall2003;
	  by ssn;
	  run;