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.
dont the authors define their notation the first time they use it?
$\displaystyle \displaystyle \delta_x ^2$ is a notation i've seen for the variance before
$\displaystyle \displaystyle \hat{\delta_x ^2}$ is a plausible notation for the estimate of the variance
$\displaystyle \displaystyle \bar{\delta_x ^2}$ 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
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
YouTube - The Basics of Physics I - How to derive the uncertainty principle
http://farside.ph.utexas.edu/teaching/qmech/qmech.pdf