Hi, I'm not a stats expert, but I believe there's a mistake in the implementation of the "right" tail case in vartest.

Current code:

elseif (strcmpi (tail, "right"))
    pval = chi2cdf (chisqstat, df);
    if (nargout > 2)
      ci = cat (dim, sumsq ./ chi2inv (1 - alpha, df), Inf (size (pval)));
    endif

The current implementation actually returns the same result as the "left" tail.