exportPattern("^[[:alpha:]]+")
importFrom("stats", "cov2cor", "optim", "deriv", "pchisq", "coef", "formula", "resid", "sigma", "qnorm", "qt", "qf", "uniroot", "terms")
importFrom("numDeriv", "hessian")
importFrom("graphics", "par", "plot", "abline", "arrows", "polygon", "text", "title")
importFrom("grDevices", "dev.new", "dev.cur")
