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Dispersion or standard deviation?

  1. Mar 22, 2014 #1
    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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  3. Mar 22, 2014 #2

    Meir Achuz

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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.
  4. Mar 22, 2014 #3


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    "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.
  5. Mar 22, 2014 #4
    What name you use for ##\Delta \hat{x}##? What is that mathematically for you?
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