Quotient regression (NR), questions and data sets

ptillmann's picture

Dear friends in NIR spectroscopy,

Data sets:
David Hopkins gave in NIR news 2016 a nice introduction to Norris regression. He uses two wheat data sets "WheglA" and "WheglB", which seem to originate from Karl's Lab.

Emails to the contact address of David from the article bounce. Does anyone have these two datasets and can provide them for me?

Does anyone know whether Karl used any kind of scatter correction prior to derivatives? If I read carefully my perception is the only modifcation to the absorption data used are derivatives.




dwhopkins's picture

Hi Peter,

I was not able to upload any files, and could not even edit my earlier reply.

The data files are 199 KB each, so that should not have been a problem.  Please send me your email, and I will be glad to send you the data files.  I can send you the dqm.m file too, if you would like to try it.  It runs under Matlab, and has a full set of utilities to look at data and run regressions or predictions.

Best wishes,



ptillmann's picture


here my email address:
[email protected]


Thank you 


ianm's picture

Dave Hopkins has sent me the data files and I am uploading them. Since there are restrictions on file extensions that can be uploaded to the server, I have zipped them and uploaded the ZIP archive.

Thanks Dave!


Uploaded Files: