The determination of the concentrations of molecules in samples has long been an important application of spectroscopy. In the last 20 years, advances in algorithms, computers, instruments, and software have led to a growing interest in this field. These developments mean samples and analytes that were once considered intractable are increasingly yielding usable calibrations. The purpose of this book is to give readers, without an advanced math background, a thorough grounding in the theory and practice of modern quantitative spectroscopic analysis. The author has placed great emphasis on providing the reader with everything they need to know to obtain a fundamental understanding of quantitative spectroscopy. In this book, relevant theory is explained in an easy to understand, conversational style; and actual spectroscopic data and calibrations are used throughout the book to show how real world calibrations are achieved. The complexities of Factor Analysis (PCR/PLS) algorithms are explained in pictures and words, making them understandable for all. Written from a spectroscopic rather than a mathematical point of view. The relevant theory is interspersed with practical discussions in order to make difficult concepts easier to comprehend. It is a comprehensive introduction for novices, and an excellent reference for experts. The topics on spectroscopy are included to emphasize its importance in quantitative spectroscopy.