Follow-up: [R] Inverse prediction with R?

Bill Simpson wsi at
Tue Feb 22 15:18:19 CET 2000

You fit
y = a+b*x

Then you get the inverse regression estimate

x = (y-a)/b

I don't see what is hard about that.

As for the confidence interval for x, try bootstrapping:
- randomly sample your (x,y) data
- do the y = a+b*x fit
- get the estimate x = (y-a)/b
- use the bootstrapped x distribution to get your CI

Or use the formulas you saw in a book.

I don't see this as a hard programming project. (I am no ace R programmer


r-help mailing list -- Read
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at

More information about the R-help mailing list