Chemometrics means performing calculations on measurements of chemical data. This can be anything from- calculating pH from a measurement of hydrogen ion activity to computing a Fourier transform interpolation of a spectrum.
More recently, the common usage of the word refers to using linear algebra calculation methods, to make either quantitative or qualitative measurements of chemical data, primarily spectra. Nearly all trained spectroscopists have the basic understanding of the concepts necessary to apply these methods. Unfortunately, like all specialty areas of science, chemometrics has a language all its own that makes it difficult for the beginner to understand.
The science of chemometrics gives spectroscopists many different ways to solve the calibration problem for analysis of spectral data. Some are very simple to understand, while others require a strong background in linear algebra. However, they all have one thing in common: they each solve an individual problem but do not address ALL possible problems. Some methods have the advantage of being simple to understand but may not be very robust for all possible samples. Others are very complex to understand and implement, but give solutions that are very stable and can handle a large variety of "unknowns."
The key to understanding chemometrics is in not necessarily understanding the mathematics of all of the different methods; it is to know which model to use for a given analytical problem and properly applying it.
Regression plot using Chemometrics software
Various chemometric methods are applied for the analysis of complex data in a number of applications viz.