options nocenter;
goptions reset=global colors=(none);

data problem81;
 infile 'i:\.www\datasets502\EX0502.DAT' firstobs=2 dlm='09'x;
 input person sbp quet age smk;
 quet_smk = quet*smk; quet_age = quet*age;

proc reg corr;
 model sbp = quet smk quet_smk;
 model sbp = quet age quet_age;
 model sbp = quet smk age quet_age quet_smk / pcorr1;
run;

proc reg;
 model sbp = quet age smk;
 model sbp = quet age;
 model sbp = quet smk;
 model sbp = quet;
 model sbp = quet age quet_age smk;
 model sbp = quet age quet_age;
run;