* Study on the heart rate and the physical activity;
option nodate;
title "Stepping up the heart rate";

proc format;
value hei 0="Low height" 1="High height";
value fre 0="Low freq." 1="Medium freq." 2="High freq";
Data heart;
infile "c:\csc423\week9\stepping.txt";
input order block height freq restHR HR;
label order = "trial order" block = "block number" 
	height = "step height" freq = "rate of stepping" 
	restHR = "resting heart rate" HR = "heart rate";
format height hei.;
format freq fre.; 
dum_freq1=(freq=1);
dum_freq2=(freq=2);

proc sort;
by freq;
/* summary statistcs for the heart rate by frequency level*/
proc means n mean stddev median q1 q3 min max;
by freq;
var hr;
/* draw side-by-side box plots*/
proc boxplot;
plot hr*freq;
/* regression analysis - ANOVA model*/
proc reg;
model hr=dum_freq1 dum_freq2;
test dum_freq2-dum_freq1=0;
plot student.*predicted.;
plot npp.*student.;
run; quit;