Back to basics: removing multiplicative effects (1)

Columns

01 Aug 2007

A.M.C. Davies^a and Tom Fearn^b
^aNorwich Near Infrared Consultancy, 75 Intwood Road, Cringleford, Norwich NR4 6AA, UK. E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
^bDepartment of Statistical Science, University College London, Gower Street, London WC1E 6BT, UK. E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Introduction

The last TD column showed the effect of calculating second derivatives on a set of 100 spectra, which will be the starting point for this column. In order to remind you where we had got to, the last graph is plotted again as Figure 1. You may have been surprised that it was suggested that these second derivative spectra still contain irrelevant variability. The plan was that in this column we would discuss the two most popular methods of removing what is known as “multiplicative effects”, but we realised that in order to understand why we want to remove it you need to know where it has come from.

pdf Full Text (3.42 Mb)