Initialization method for the "DualEndpointOld" class
# S4 method for DualEndpointOld
initialize(.Object, mu, Sigma, sigma2betaW,
sigma2W, rho, smooth = c("RW1", "RW2"), ...)
either “RW1” (default) or “RW2”, for specifying the random walk prior on the biomarker level.
not used