Posts Tagged ‘ "R" Chemometrics ’

Removing "Y" outliers from the "Validation Set"

June 3, 2012
By
Removing "Y" outliers from the "Validation Set"

This is a new video about how to monitor and interpret statistics and graphics for validation. Removing "Y" outliers from Validation SetPrevious videos about the Monitor function  for validation:Should I adjust the Bias?Monitor: Adding "RER" and "...

Read more »

Exporting from Win ISI / Importing into R

May 29, 2012
By
Exporting from Win ISI / Importing into R

Chemometric software´s  have the option to export a matrix to a TXT file (in this case a constituents matrix), in a way we can import it easily into R, to work with. It is the first step to go into the R world.I use in this case Win ISI Soft...

Read more »

Mahalanobis distance with "R" (Exercice)

May 29, 2012
By
Mahalanobis distance with "R" (Exercice)

I have developed this exercise with Excel in another post for the same calculations , I am going to develop  it this time with  "R".    edad  long.  peso    mg.kg1    28 &n...

Read more »

Monitor: Adding "RER" and "RPD" statistics

May 25, 2012
By
Monitor: Adding "RER" and "RPD" statistics

I continue developing the Monitor function in R. The idea is to get statistics which help me to understand the performance of my model.Of course the validation set must be free of outliers (X or Y).I add this time two new statistics: RER and ...

Read more »

Monitor: Removing zero values from the data set.

May 17, 2012
By
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...

Read more »

Improving script_002: “Monitor”

May 15, 2012
By
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...

Read more »

Should I adjust the Bias?

May 10, 2012
By
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 ...

Read more »

Improving script_001: “Monitor”

May 6, 2012
By
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...

Read more »

Practicing Script with “ R”: Monitor

May 4, 2012
By
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 ...

Read more »

Monitoring some statistics with "R"

May 1, 2012
By
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...

Read more »