proc phreg, result of 'assess' statement, Standardized score process plot

[likestat]

Hi,

I have a question for the use and result of 'assess' statement in SAS proc phreg.

I used the following code. I got plot of Standardized Score Process and p_value.
I found the p_value for the testing of Proportional Assumption changes for different run.

How to explain the plot? And how to explain the changes of the p_value for the testing? Due to resampling? I am not familiar with the inside calculation.

Thanks a lot!!


ods graphics on;

proc phreg data = days;
class trt;
model pfsdays*cen(1) = trt / rl;
assess ph resample;
run;

ods graphics off;

[likestat]

No one answer? I really hope to understand the basic of the plot.

What does the Standardized score process (y_value) mean?

I tried more. If I use difference reference in the code, the plot just is like a mirror opposite. All positive values become negative vallues but the absolute values seems just the same.

Thanks a lot!!


ods graphics on;

proc phreg data = days;
class trt (ref = 'A'); **or ref = 'B';
model pfsdays*cen(1) = trt / rl;
assess ph resample;
run;

ods graphics off;