R : Copyright 2006, The R Foundation for Statistical Computing
Version 2.3.1 (2006-06-01)
ISBN 3-900051-07-0

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> require(chemCal)
Loading required package: chemCal
[1] TRUE
> data(massart97ex3)
> attach(massart97ex3)
> yx <- split(y, x)
> ybar <- sapply(yx, mean)
> s <- round(sapply(yx, sd), digits = 2)
> w <- round(1 / (s^2), digits = 3)
> weights <- w[factor(x)]
> m <- lm(y ~ x, w = weights)
> #calplot(m)
> 
> inverse.predict(m, 15, ws = 1.67)  # 5.9 +- 2.5
$Prediction
[1] 5.865367

$`Standard Error`
[1] 0.892611

$Confidence
[1] 2.478285

$`Confidence Limits`
[1] 3.387082 8.343652

> inverse.predict(m, 90, ws = 0.145) # 44.1 +- 7.9
$Prediction
[1] 44.06025

$`Standard Error`
[1] 2.829162

$Confidence
[1] 7.855012

$`Confidence Limits`
[1] 36.20523 51.91526

> 
> m0 <- lm(y ~ x) 
> lod(m0)
$x
[1] 5.406637

$y
[1] 13.63822

> 
> loq(m0)
$x
[1] 13.97767

$y
[1] 30.62355

> loq(m, w.loq = 1.67)
$x
[1] 7.346231

$y
[1] 17.90784

>