With this code
\documentclass{minimal}
\usepackage{amsmath}
\begin{document}
${\bar{S}}_{\text{rel,t}}$
\end{document}
I get
How can I extend the \bar over the subscript?
[Tex/LaTex] How to get a \bar over a subscript
math-modespacingsubscriptssymbols
Related Solutions
Certainly something like $\overline{A_1}$, because it is closure of $A_1$. But I understand, that the rule may look a bit too long for you. Indeed, there is no italic correction for math font. If you prefer a bit shorter version, see, e.g. answers to Appearance issues with \bar{} and \underline{}.
I can't explain why the problem arises in the first place, but one solution is to box the initial item, and apply the \hat at the end. I also provide a 2nd alternative where I apply the \hat only to the \sigma; that may be preferable.
\documentclass{article}
\usepackage{amsmath}
\begin{document}
$
\setbox0=\hbox{$\sigma^2_{\bar{X}}$}
\hat{\box0}
$
$\setbox0=\hbox{$\hat\sigma$}\box0^2_{\bar{X}}$
\end{document}
If one wanted the first approach, but with a really wide hat, my answer at Really wide hat symbol might be applicable:
\documentclass{article}
\usepackage{scalerel,stackengine}
\stackMath
\newcommand\reallywidehat[1]{%
\savestack{\tmpbox}{\stretchto{%
\scaleto{%
\scalerel*[\widthof{\ensuremath{#1}}]{\kern-.6pt\bigwedge\kern-.6pt}%
{\rule[-\textheight/2]{1ex}{\textheight}}%WIDTH-LIMITED BIG WEDGE
}{\textheight}%
}{0.5ex}}%
\stackon[1pt]{#1}{\tmpbox}%
}
\usepackage{amsmath}
\begin{document}
$
\reallywidehat{\sigma^2_{\bar{X}}}
$
\end{document}
Best Answer
Does this help (
\overlineinstead of\bar)?Related