/* Tracking observations with IN= option */
* This data set does not include all the observations 
 of the previous student data set;
/* Some students are missing from the test file or the HW file */

data tests;
INPUT student $ period test1-test3;
lines;
Susan 2 81 93 100
Arnold 1 72 83 72
Barbara 1 91 72 84
Johnny 3 62 79 80
Sandra 3 98 74 90
;
run;

data homework;
INPUT student $ period hw1-hw4;
lines;
John 1 8 7 3 5 
Billy 2 9 7 9 10
Susan 2 9 6 9 8
Arnold 1 7 9 6 10
Barbara 1 6 9 7 8
;
run;

proc sort data=tests;
by student;

proc sort data=homework;
by student;

data allgrade;
merge tests (IN = InTest) homework (IN = InHomework);
by student;
IF InTest = 1 THEN Test = 'Yes'; 
IF InTest = 0 THEN Test = 'No'; 
IF InHomework = 1 THEN HW = 'Yes'; 
IF InHomework = 0 THEN HW = 'No'; 
run;

proc print data=allgrade;
title 'Grades & data set each obs came from';
run;