Weighted Kaplan Meier

[longitudinal]

Dear communities,

I am wondering if anyone can answer this question:

I want to get the weighted Kaplan Meier survival estimation/curve through Proc Phreg with "product-limit" option specified. However, I cannot find the background calculation/formula that SAS used to generate the survival estimation, could you point the paper I can refer to? The weight I am using is the ratio of the 1: M matched (case/control). 

Thank you!

[Rick_SAS]

I don't know the answer to your exact question, but in case it helps, a general weighted cumulative distribution (similarly, a survival distribution) is adjusted by weights as explained in the article "Weighted percentiles."

[longitudinal]

Thank you! I will look into it.