help with predict and plotting confidence intervals
On Mar 12, 2009, at 11:45 AM, David Winsemius wrote:
On Mar 12, 2009, at 11:14 AM, Michael Denslow wrote:
# I am not sure how to get the lines to draw correctly here matlines(pred.frame$a,pp, lty=c(1,2,2),col="black")
The x values are your sequence whereas the y values are in the sequence from the original data. They are not correctly associated with each other. Try: pp <- predict(lm(wt.data$logS~wt.data$logA), int = "p", newdata= data.frame(logA=seq(0,6, length.out = 24)) ) plot(pp)
At this point I should not have accepted your starting point. A better starting point would be to use the wt.mod model: pp <- predict(wt.mod, int = "p", newdata= list(logA=seq(0,6, length.out = 24)) ) # Followed by: plot( seq(0,6, length.out = 24), pp[ ,"fit"] ) lines(seq(0,6, length.out = 24), pp[ ,"lwr"], lty=2) lines(seq(0,6, length.out = 24), pp[ ,"upr"], lty=2)
-- david winsemius
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David Winsemius, MD Heritage Laboratories West Hartford, CT