Blog Archives

Monitor: Removing zero values from the data set.

May 17, 2012
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Monitor: Removing zero values from the data set.

I continue developing the Monitor function. This time a video from  "r twotorials”: “how to access different records within a data frame by using logical tests in r”, gave me the idea to remove the zero values from a data set.When somebody g...

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Improving script_002: “Monitor”

May 15, 2012
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Improving script_002: “Monitor”

I read in an article that Ian Cowe said that what normally chemometricians do is to look to the graphics, of course interpret those graphics. So I still go on trying to develop a function can help me to understand the graphics and all the statistics th...

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Should I adjust the Bias?

May 10, 2012
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Should I adjust the Bias?

A bias or systematic error is quite common when monitoring predictions vs reference data. Anyway we must have certain control limits to decide if the Bias is significant or not. Procedures (as for example ISO 12099 )give details about how to calculate ...

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Improving script_001: “Monitor”

May 6, 2012
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Improving script_001: “Monitor”

After having a look to this video: http://www.screenr.com/UxH8 from rtwotutorials, and reading some tutorials, I decided to modified the script from the previous post: Practicing Script with “ R”: Monitor , in order to make it more r...

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Practicing Script with “ R”: Monitor

May 4, 2012
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Practicing Script with “ R”: Monitor

These are  samples analyzed by a reference method (column: Protein) and by an analytical method with a certain model (column: IFTpro). The idea is to create a Monitor Report for some basic statistics (RMSEP, Bias, SEP, R,RSQ) to see how ...

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Monitoring some statistics with "R"

May 1, 2012
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Monitoring some statistics with "R"

I´ve been practicing after reading a couple of tutorials:R: A self-learn tutorialProgramming in Rto create a basic function  to monitor some  basic statistics as RMSEP, Bias, SEP, Correlation and RSQ. I´ve been doing this with other so...

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R^2 Spectrum

April 21, 2012
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R^2 Spectrum

We have seen in the previous post, how to calculate the correlation spectrum, but other simple way to show  how the bands correlate to the constituent of interest is to calculate R^2. This way we remove the negative part of the correlation spectru...

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"Correlation / Covariance" Spectrum (This time with "R")

April 18, 2012
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"Correlation / Covariance"  Spectrum (This time with "R")

I treat this matter with other software´s, and of course you can do the same with "R".Once I have the spectra of my samples with a math treatment, I want to draw a correlation spectrum to see which wavelengths have better correlation with the constitu...

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More Spectra patterns (1ª derivative)

April 17, 2012
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More Spectra patterns (1ª derivative)

In the case of the first derivative for the absortion band, the maximum becomes a cero crossing.Using SG filters, we can calculate it with R, and to see, like in the last posts, the Corrgram matrix.Corrgram for the first derivative for this band:L...

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Math Spectra Patterns

April 16, 2012
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Math Spectra Patterns

I was working today with "R" to get more patterns with the Corrgram. In the demo raw spectra I wanted this time to look to a band as much Gaussian as possible. I select it and trim the spectra to that region treated with the MSC ("Multiple Scatter Corr...

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