AHeVT                   AHe V(t)-approach
AHeVXT                  AHe V(X(t),t)-approach
CD4                     The CD4 dataset
QRIndiv                 Individual quantile objective function
QRSimul                 Unweighted simultaneous objective function
QRStepwise              Stepwise procedure
QRWSimul                Weighted simultaneous objective function
test_variability        Variability Estimation and Testing
