Difference between stratified and unstratified

[chinna0369]

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

[Reeza]

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?

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@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

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[chinna0369]

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,

[Reeza]

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

[Reeza]

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.

[chinna0369]

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

[Reeza · Accepted solution]

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

[chinna0369]

Thank you so much!