Quartz | Level 8

## weight statement in proc lifetest

Hello,

Under weight statement, what kind of weight can be put in ?

Dose the weight only allow IPW(inverse probability of treatment weights) or any kind of weight from the weighting method such as entropy balance, propensity score matching ?

https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.4/statug/statug_lifetest_syntax08.htm

```proc lifetest data=VALung ;
time SurvTime*Censor(1);
strata Cell;
weight ????  ;
run;```

Thank you!

2 REPLIES 2
Super User

## Re: weight statement in proc lifetest

From the documentation of the Weight statement for Proc Lifetest:

The implementation of weights in PROC LIFETEST is based on Xie and Liu (2005, 2011), who use inverse probability of treatment weights to reduce confounding effects. A weight is assigned to each subject as the inverse probability of being in a certain group. If a subject has a higher probability of being in a group, it is considered as overrepresented and is therefore assigned a lower weight; on the other hand, if the subject has a smaller probability of being in a group, it is considered as underrepresented and is assigned a higher weight.

So it appears that only IPW is expected.

@Ivy wrote:

Hello,

Under weight statement, what kind of weight can be put in ?

Dose the weight only allow IPW(inverse probability of treatment weights) or any kind of weight from the weighting method such as entropy balance, propensity score matching ?

https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.4/statug/statug_lifetest_syntax08.htm

```proc lifetest data=VALung ;
time SurvTime*Censor(1);
strata Cell;
weight ????  ;
run;```

Thank you!

SAS Employee

## Re: weight statement in proc lifetest

I think IPW weights are common but you should be able to use any WEIGHT value you desire. Note that the WEIGHT stmt only applies to Method=KM.
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