topic Re: what that code does mean? in SAS Programming

what that code does mean?

bigban777 — Sun, 27 Mar 2016 18:02:20 GMT

DATA covprob;
p = .5;
q = 1-p;
z=abs(probit(.025));
zz=z*z;
do n = 10 to 500;
w = zz / (2 * n);
rad = sqrt(2*w*p*q + w*w);
rt = (p + w + rad)/(1 +2*w);
lt = (p + w - rad)/(1 +2*w);
nhat_rt = floor(n*rt);
nhat_lt = ceil(n*lt - 1);
ncurl_rt = floor((n+4)*rt - 2);
ncurl_lt = ceil((n+4)*lt - 3);
p1 = probbnml(p, n, nhat_lt);
p2 = probbnml(p, n, nhat_rt);
cv_hat = p2 - p1;
p3 = probbnml(p, n, ncurl_lt);
p4 = probbnml(p, n, ncurl_rt);
cv_curl = p4 - p3;
output;
end;
keep n cv_hat cv_curl;
run;

 
 
PROC plot data = covprob;
plot cv_hat*n = '^';
plot cv_curl*n = '~';
run;
quit;

Re: what that code does mean?

Reeza — Sun, 27 Mar 2016 18:04:42 GMT

In what context? Is there a specific part you don't understand?

Are you looking for an explanation of a specific line?

Where did you find this code and what are you trying to do with it?

Re: what that code does mean?

PGStats — Sun, 27 Mar 2016 19:31:21 GMT

It looks like some sort of power analysis for (binomial) proportions. But why reverse engineer this undocumented code? Understand the problem and write your own. And document it!

Re: what that code does mean?

Reeza — Sun, 27 Mar 2016 21:18:00 GMT

If it is power analysis it's likely proc power would likely be a better implementation as well 🙂

Re: what that code does mean?

bigban777 — Sun, 27 Mar 2016 21:34:24 GMT

That part:
nhat_rt = floor(n*rt);
nhat_lt = ceil(n*lt - 1);
ncurl_rt = floor((n+4)*rt - 2);
ncurl_lt = ceil((n+4)*lt - 3);

Is it interval? Why it is subtracte -1, -3