* Add title to output;
title "Mortage refusal rate by applicant racial profile";
/* options in infile statement
 * delimiter = "09"x specifies data are spaced by Tabs;
 * firstobs = n specifies first obs is in n-th row;
 */
data mortgage;
infile "C:\Documents and Settings\rsettimi\My Documents\Courses\CSC423\Lecture Notes\Week3\mortgage_refusal_rate.txt" 
delimiter = "09"x firstobs=4;
input bank $ minor white;
differ=minor-white;

/* One way of computing paired t-test: proc univariate on variable differ, 
see tests on average results. This is useful to check normality assumptions.  */
proc univariate normal plot; 
var differ;
histogram/ normal cfill=white pfill=solid ;
probplot/ normal (mu=est sigma=est color=blue l=1 w=1);
run;

/* Second way of computing paired tests: use ttest procedure & paired statement*/
proc ttest data=mortgage;
paired minor*white;
run;

proc gplot;
plot (minor white)*white/overlay;
run;