loess line not plotting correctly

Question

I\'m having trouble fitting a loess smooth plus confidence limits to a scatterplot of residuals.

My model is height ~ weight + chest circumference. To check linearit

Answer 1

lines connects the points in the order in which they appear, which is sometimes undesirable. You can sort them as follows:

i <- order(bf.red$chestc)
lines(bf.red$chestc[i], lo.pred$fit[i])
...