5. General Key Concepts

This chapter is intended to help readers recognize the computational equivalence of the concepts listed below. The equivalence refers to the fact that they all represent the average distance from the center.

Research Field	Concept
Statistics	\(\sigma\) (standard deviation)
Chromatography	\(\sigma\) (associated with peak width)
Structure Size Measure	Rg - radius of gyration

In relation to these concepts, an introduction to the characteristic function will follow, which is used later in the stochastic theory of SEC.