topic Re: Difference between stratified and unstratified in SAS Programming

Difference between stratified and unstratified

chinna0369 — Tue, 30 Apr 2019 17:12:53 GMT

Hi,

I am trying to get stratified and unstratified P-values and Hazard ratios. can anyone help me to identify the difference between stratified and unstratified proc lifetest code and proc phreg code in sas?

Thank you in advance!

Adithya

Re: Difference between stratified and unstratified

Reeza — Tue, 30 Apr 2019 17:38:40 GMT

Both have STRATA statements to specify the STRATA specifically, which would allow you to easily see if the analysis was stratified or no.

Is there something else you're looking for?

@chinna0369 wrote:

Hi,

I am trying to get stratified and unstratified P-values and Hazard ratios. can anyone help me to identify the difference between stratified and unstratified proc lifetest code and proc phreg code in sas?

Thank you in advance!

Adithya

Re: Difference between stratified and unstratified

chinna0369 — Tue, 30 Apr 2019 17:51:16 GMT

Hi Reeza,

Thank you for your reply!

below code I am using,

** P-value;
ods trace on;
ods output LogUniChiSq=pval;

proc lifetest data=adtte outsurv=surv alpha=0.05;
time aval * cnsr(1);
test trtpn;
run;

ods trace off;
ods output close;

From the output of above code, how can I recognize the values is from stratified or unstratified?

Thanks,

Re: Difference between stratified and unstratified

Reeza — Tue, 30 Apr 2019 19:53:23 GMT

You don't have a STRATA statement so you have no stratification.

Re: Difference between stratified and unstratified

Reeza — Tue, 30 Apr 2019 20:00:09 GMT

This assumes you're referring to the statistical concept of stratification which is analyzing data by strata/groups creating separate models that use the same terms. If you're not using that definition, which I'm starting to suspect then the answer will differ. Please clarify.

Re: Difference between stratified and unstratified

chinna0369 — Wed, 01 May 2019 20:10:15 GMT

Hi Reeza,

I understand now and I have updated my code as below:

ods output HomTests=pval;

proc lifetest data=adtte outsurv=surv alpha=0.05;
time aval * cnsr(1);
strata ACCRES/group= trtpn;
run;

and now I am getting statified P-values based on Two-sided stratified Log-Rank test based on the stratification of ACCRES.

Now how can I get p-value based on Two-sided unstratified Log-Rank test? by using above code?

Thank you in advance!

Adithya

Re: Difference between stratified and unstratified

Reeza — Wed, 01 May 2019 20:28:23 GMT

unstratified is what you had before - ie no STRATA statement.

Re: Difference between stratified and unstratified

chinna0369 — Wed, 01 May 2019 20:29:38 GMT

Thank you so much!