Dispersion or standard deviation?

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Discussion Overview

The discussion revolves around the terminology used in statistics and probability, specifically regarding the terms "dispersion" and "standard deviation" as they relate to the expression for the uncertainty in a coordinate, denoted as ##\Delta \hat{x}##. The scope includes conceptual clarification and technical explanation of statistical measures.

Discussion Character

  • Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants assert that ##\Delta \hat{x}## is referred to as the standard deviation, defined mathematically as ##\Delta \hat{x}=(\langle \hat{x^2} \rangle-\langle \hat{x} \rangle ^2)^{\frac{1}{2}}##.
  • One participant expresses unfamiliarity with the term "dispersion of coordinate," suggesting it may be a translation issue.
  • Another participant notes that "standard deviation" is commonly used, and distinguishes it from "variance," while explaining that "dispersion" is a broader concept related to the spread of a statistical distribution.
  • A participant asks for clarification on what others call ##\Delta \hat{x## and seeks to understand its mathematical interpretation from different perspectives.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the terminology, with differing views on the use of "dispersion" versus "standard deviation." Multiple competing interpretations remain present in the discussion.

Contextual Notes

There are limitations in the discussion regarding the definitions of "dispersion" and "standard deviation," as well as the context in which these terms are used. The mathematical steps and assumptions underlying the definitions are not fully resolved.

LagrangeEuler
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In some textbooks ##\Delta \hat{x}## is called dispersion of coordinate ##\Delta \hat{x}=(\langle \hat{x^2} \rangle-\langle \hat{x} \rangle ^2)^{\frac{1}{2}}##. For me that is standard deviation. What do you think?
 
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I have never seen 'dispersion of coordinate' used. It strikes me as something translated from English to another language, and then translated back.
 
"Standard deviation" is the term that I've always used; or for its square, the "variance".

A Google search for "dispersion standard deviation" turns up many pages with statements like "the standard deviation is a measure of dispersion". So "dispersion" is the general idea of "width" of a statistical distribution, and the "standard deviation" is a specific way of describing or measuring it mathematically.
 
What name you use for ##\Delta \hat{x}##? What is that mathematically for you?
 

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