bon alors j'ai fait ça : >survie.cox<-boxcox(V4~V1, data = a, lambda = seq(-2, 2, length = 10)) > survie.cox<-boxcox(V4~V3, data = a, lambda = seq(-2, 2, length = 10)) > survie.cox<-boxcox(V4~V1+V3, data = a, lambda = seq(-2, 2, length = 10)) qu'en pen...