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

[Bill Simpson]

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
myself)

Bill

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