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In case you missed them, here are some articles from January of particular interest to R users. Sponsorships from Revolution Analytics are now available for local R user groups in 2012. The winners of the Applications of R in Business Contest have been announced. The coefplot package visualizes model coefficients and standard errors in a line chart. Revolution Analytics...

MSC (Multiple Scatter Correction) is a Math treatment to correct the scatter in the spectra. The scatter is produced for different physical circumstances as particle size, packaging.Normally scatter make worse the correlation of the spectra with the constituent of interest.Almost all the chemometric software’s available include this math treatment and of course “R” have it as well in the...

In the previous post we plot the Cross Validation predictions with:> plot(gas1, ncomp = 3, asp = 1, line = TRUE)We can plot the fitted values instead with:> plot(gas1, ncomp = 3, asp = 1, line = TRUE,which=train) Graphics are different:Of course, using "train" we get overoptimisc statistics and we should look...

The gasoline data set has the spectra of 60 samples acquired by diffuse reflectance from 900 to 1700 nm. We saw how to plot the spectra in the previous post.Now, following the tutorial of Bjorn-Helge Mevik published in "R-News Volume 6/3, August 2006", we will do the PLS regression:gas1 <- plsr(octane~NIR, ncomp = 10,data = gasoline, validation...

As other softwares "R" has nice tools to look to the data before to develop the calibration.Statistics for the "Y" variable (in this case octane number) like Maximun, Minimun,..,standard deviation,...are important:> library(ChemometricsWithR)> data(gasoline)> summary(gasoline$octane) Min. 1st Qu. Median Mean 3rd Qu. Max. 83.40 85.88 87.75 87.18 88.45 89.60> sd(gasoline$octane) 1.530078And of course the Histogram:> hist(gasoline$octane)

The 8th international R users conference useR! 2012 will be in Nashville TN USA June 12-15 with a special all-day pre-conference course from Bill Venables on June 11. We have a terrific lineup of half-day tutorials on June 12 and will have invited and contributed presentations of interest to a wide variety of R users. Details may be found...