1 files changed, 21 insertions, 2 deletions
diff --git a/man/inverse.predict.Rd b/man/inverse.predict.Rd
index 26ba6b8..373623e 100644
--- a/man/inverse.predict.Rd
+++ b/man/inverse.predict.Rd
@@ -52,7 +52,10 @@
 }
 \note{
   The function was validated with examples 7 and 8 from Massart et al. (1997). 
-}
+  Note that the behaviour of inverse.predict changed with chemCal version
+  0.2.1. Confidence intervals for x values obtained from calibrations with
+  replicate measurements did not take the variation about the means into account.
+  Please refer to the vignette for details.}
 \references{
   Massart, L.M, Vandenginste, B.G.M., Buydens, L.M.C., De Jong, S., Lewi, P.J.,
   Smeyers-Verbeke, J. (1997) Handbook of Chemometrics and Qualimetrics: Part A,
@@ -60,10 +63,26 @@
 }
 \examples{
 # This is example 7 from Chapter 8 in Massart et al. (1997)
-data(massart97ex1)
 m <- lm(y ~ x, data = massart97ex1)
 inverse.predict(m, 15)        #  6.1 +- 4.9
 inverse.predict(m, 90)        # 43.9 +- 4.9
 inverse.predict(m, rep(90,5)) # 43.9 +- 3.2
+
+# For reproducing the results for replicate standard measurements in example 8,
+# we need to do the calibration on the means when using chemCal > 0.2
+weights <- with(massart97ex3, {
+  yx <- split(y, x)
+  ybar <- sapply(yx, mean)
+  s <- round(sapply(yx, sd), digits = 2)
+  w <- round(1 / (s^2), digits = 3)
+})
+
+massart97ex3.means <- aggregate(y ~ x, massart97ex3, mean)
+
+m3.means <- lm(y ~ x, w = weights, data = massart97ex3.means)
+
+inverse.predict(m3.means, 15, ws = 1.67)  # 5.9 +- 2.5
+inverse.predict(m3.means, 90, ws = 0.145) # 44.1 +- 7.9
+
 }
 \keyword{manip}