So when I do the following:

EXP(16.1+ (var1*-0.08) + (var2*-.27) + (var3*-.28) + (ln(-ln(1-.5))/1.1)

EXP(intercept + B1*var1 + B2*var2 + ......+ Bx*varX + ln(-ln(1-%ile)) / shape)

I get the same exact answers as what SAS outputs.

The ln(-ln(1-.5) I saw on a SAS website (http://support.sas.com/documentation...eg_sect020.htm)

Where the .5 represents the median.

Just curious if anyone can confirm that this is truly how to calculate the estimated median survival by hand (it seems like it would be more than just coincidence that this got me exactly what SAS gave me).