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Math Help - Basic Question about Variance

  1. #1
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    Basic Question about Variance

    For example for variance of delta x, some sources have it as (delta*x)^2 with a bar on top, and others show it as <(delta*x)^2>. Are they referring to the same thing?

    Thanks.
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  2. #2
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    dont the authors define their notation the first time they use it?

    \displaystyle \delta_x ^2 is a notation i've seen for the variance before

    \displaystyle  \hat{\delta_x ^2} is a plausible notation for the estimate of the variance

    \displaystyle  \bar{\delta_x ^2} i've never seen and wouldn't understand if i saw it.


    NB i edited the content of this post while OP was typing the reply below
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  3. #3
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    Here are the sources. The first is a youtube video (watch at the beggining he says variance of delta x), and for the second one, go to page 10, equation 2.19



    http://farside.ph.utexas.edu/teaching/qmech/qmech.pdf
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