options ls=75;
/*
This is a program for sample sizes for a matched case-control
study.
Input below after cards statement.
p0=Control Positivity Rate (probability control has exposure)
or=Odds ratio (Relative Risk) to be detected
alpha=p-value (two sided).  Double it for one-sided 
power=Power sought for study

Output:
Calculates exposure probability for cases for the given odds ratio
For 1,2,3,4, and 5 Controls per case, it gives sample sizes for 
     cases, controls, and total.
*/
data a;input p0 or alpha power;
cards;
.25 1.75 .05 .8
.25 1.7 .05 .8
.25 1.5 .05 .8
.30 1.5 .05 .8

data a;set a;

if alpha>1 then alpha=.01*alpha;
if power>1 then power=.01*power;
beta=1-power;
za=probit(1-.5*alpha);
zb=probit(1-beta);
p1=or*p0/(1-p0+or*p0);
check=p1*(1-p0)/(p0*(1-p1));
do m=1 to 5;
h=(1/(p1*(1-p1)))+ (1/(M*p0*(1-p0)));
n=(((za+zb)/log(or))**2)*h;
n=int(1+n);ncase=m*n;total=n+ncase;
output;
end;
data a;set a;
file print;
power=1-beta;
k=_n_;
if k=1 then do;
put // @20 'Matched Case-Control Sample Size Program' //
       @20 'Tests are two-sided' // ; 
put @3 'Control'  @13 'Odds' @22 'Case'  @28 'Controls' @38  'P-Value' 
@46 'Power' @53 'Cases' @62 'Controls' @71 'Total' /
@3 'Rate'  @13 'Ratio' @22 'Rate' @28 'Per Case'  
@53 'Needed' @62 'Needed';
end;
put @3 p0 @13 or @22 p1 best5.  @30 m @38 alpha @46 power @53 n @62 ncase @71 total;
run;