how to construct a survival model what is the matrix for survival analysis what is the value of vcov in survival what is the vcov matrix for survival what is the vcov matrix how to make a vcov matrix how does survival model work which is an extra term in the log(scale) of a survival model? which factor is a risk factor of a survival model? vcov matrix of survival what is vcov in survival model what is the value of vcov what is the vcov of survival model vcov in a survival model what are the factors that influence the survival model what the difference between a survival matrix and an age matrix vcov matrix of survival models age covariance matrix what is the vcov of survival how to create a survival model