lod <- function(object, ..., alpha = 0.05, beta = 0.05)
{
UseMethod("lod")
}
lod.default <- function(object, ..., alpha = 0.05, beta = 0.05)
{
stop("lod is only implemented for univariate lm objects.")
}
lod.lm <- function(object, ..., alpha = 0.05, beta = 0.05)
{
y0 <- predict(object, data.frame(x = 0), interval="prediction",
level = 1 - alpha)
yc <- y0[[1,"upr"]]
xc <- inverse.predict(object,yc)[["Prediction"]]
f <- function(x)
{
# Here I need the variance of y values as a function of x or
# y values
# Strangely, setting the confidence level to 0.5 does not result
# in a zero confidence or prediction interval
}
lod.x <- optimize(f,interval=c(0,max(object$model$x)))$minimum
lod.y <- predict(object, data.frame(x = lod.x))
return(list(x = lod.x, y = lod.y))
}
