chi square, greek or roman? I would like to report a chi square statistic evaluated from an experimental population in a manuscript. Do I use (1) the lower case Greek letter ($\chi^2$), (2) the upper case Greek letter ($X^2$), or (3) the standard upper case Roman letter "X" (X$^2$, as found in Microsoft Word on a standard QWERTY keyboard)?
Many thanks!

It comes down to the expectation from whoever will be reviewing your work. If you’re submitting to an academic journal, look at other articles in that journal and do what they do.
That said, I would consider the “right” answer to be the lowercase Greek letter, $\chi$, which is “\chi” in $\LaTeX$.
