Statistical Procedures

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Banoo
Obsidian | Level 7

Hello,

 

I want to find minimum and maximum for duration of response. Is there a way to get those numbers from PROC LIFETEST procedure. Mean, median and 95% CI are straight forward from the procedure. Should I use Proc means or proc summary instead.

 

My SAS code :

ods output productlimitestimates = km (keep=stratum trtpn Timelist Survival)
Quartiles =_quartiles (keep=stratum trtpn percent estimate lowerlimit upperlimit percent
where=(percent eq 50))
Means = mean
CensoredSummary =_censorsum;
proc lifetest data=want
method=KM timelist=12 24 outsurv=surv;
time dor*dorcnsr(1); /* dor - duration of response */
strata trt;
run;

 

Any help is much appreciated. Thank you !!

1 ACCEPTED SOLUTION

Accepted Solutions
FreelanceReinh
Jade | Level 19

Hello @Banoo,

 


@Banoo wrote:

I want to find minimum and maximum for duration of response. Is there a way to get those numbers from PROC LIFETEST procedure. Mean, median and 95% CI are straight forward from the procedure. Should I use Proc means or proc summary instead.


To be consistent with other quantile estimates (such as the median) using the Kaplan-Meier method -- see the "general formula for estimating the 100pth percentile point" in section Breslow, Fleming-Harrington, and Kaplan-Meier Methods of the PROC LIFETEST documentation and consider the cases p → 0 and p → 1 -- I would use

  • for the minimum: the smallest duration ("event time," i.e., excluding censored times)
  • for the maximum: the largest duration, unless it is censored, in which case the maximum cannot be estimated (cf. missing quartile estimates if the Kaplan-Meier curve doesn't drop far enough).

So, yes, you can use PROC MEANS or PROC SUMMARY, but taking the censoring flag (your variable dorcnsr) into consideration as described above.

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2 REPLIES 2
FreelanceReinh
Jade | Level 19

Hello @Banoo,

 


@Banoo wrote:

I want to find minimum and maximum for duration of response. Is there a way to get those numbers from PROC LIFETEST procedure. Mean, median and 95% CI are straight forward from the procedure. Should I use Proc means or proc summary instead.


To be consistent with other quantile estimates (such as the median) using the Kaplan-Meier method -- see the "general formula for estimating the 100pth percentile point" in section Breslow, Fleming-Harrington, and Kaplan-Meier Methods of the PROC LIFETEST documentation and consider the cases p → 0 and p → 1 -- I would use

  • for the minimum: the smallest duration ("event time," i.e., excluding censored times)
  • for the maximum: the largest duration, unless it is censored, in which case the maximum cannot be estimated (cf. missing quartile estimates if the Kaplan-Meier curve doesn't drop far enough).

So, yes, you can use PROC MEANS or PROC SUMMARY, but taking the censoring flag (your variable dorcnsr) into consideration as described above.

Banoo
Obsidian | Level 7
Thanks for your input. I took the simpler approach by using Proc Means and appending them with appropriate censoring flag.

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