***********************************************************************
* This is a program that illustrates the use of PROC FREQ in SAS for  *
* comparing two diagnostic tests based on data from two samples.      *
***********************************************************************;

proc format;
value yesnofmt 1='yes' 2='no';
run;

data sensitivity_diag1;
input positive count;
format positive yesnofmt.;
cards;
1 82
2 18
;
run;

proc freq data=sensitivity_diag1;
tables positive/binomial alpha=0.05;
weight count;
title "Exact and Asymptotic 95% Confidence Intervals for Sensitivity with Diagnostic Test #1";
run;

data sensitivity_diag2;
input positive count;
format positive yesnofmt.;
cards;
1 140
2  60
;
run;

proc freq data=sensitivity_diag2;
tables positive/binomial alpha=0.05;
weight count;
title "Exact and Asymptotic 95% Confidence Intervals for Sensitivity with Diagnostic Test #2";
run;

data comparison;
input test positive count;
format positive yesnofmt.;
cards;
1 1  82
1 2  18
2 1 140
2 2  60
;
run;

proc freq data=comparison;
tables positive*test/chisq;
exact chisq;
weight count;
title "Exact and Asymptotic Tests for Comparing Sensitivities";
run;