Introduction to Measurement and Analysis in Physiology

Abstract

Measurement of physiological signals is the first step in understanding the underlying physiological system. These measurements are based on a tentative model of the system. The measurement model postulates characteristics of the signal of interest that distinguish it from interfering noise. The two main purposes of signal analysis and systems modeling in physiology are (a) to reduce the contaminating noise in the observed signal and (b) to interpret and describe the process. Before any manner of noise reduction is performed, a conceptual model of the signal necessarily exists in the mind of the observer. It is this model that determines how effectively the “true” signal will be elucidated from the noisy recording. The selection of noise reduction techniques will depend on this conceptual model. Once the signal is cleaned by the noise reduction technique, the system may be modeled more exactly in order to obtain parameters that describe it. This chapter introduces the connections between measurement, analysis, and interpretation of physiological information.

There is one thing of which one can say neither that it is one metre long, nor that it is not one metre long, and that is the standard metre in Paris. But this is, of course, not to ascribe any extraordinary property to it, but only to mark its peculiar role in the language-game of measuring with a metre-rule.

– Ludwig Wittgenstein