I am trying to get this to work. It is supposed to have a cell (that was already created with multirow) with three rows but I do not know how to get it to work.
I am using shortstack to get it, but it is not optimal. In particular, W2=3 should be aligned with the first set of three values in the snippet below.
My guess is that I have to use multirow within multirow, but I am lost.
\begin{figure*}
\centering
\begin{tabular}{|c|c|c c c c|c|}
\hline
\multicolumn{2}{|c|}{\multirow{2}{*}{$V_{\rm rot}/{\sigma}$}}&\multicolumn{4}{c|}{W1}\\
\cline{3-6}
\multicolumn{2}{|c|}{}&3&6&9&12\\
\hline
\multirow{4}{*}{W2}& 3 & \shortstack{0.090475$\pm$ 0.011115\\0.14861$\pm$ 0.03562\\0.1861 $\pm$ 0.01728} & 21&6&3\\
& 6 &8&14&5&2\\
& 9 &8&14&5&2\\
&12 &8&14&5&2\\
\hline
\end{tabular}
\caption{Multirow in multirow}
\label{ta.Multirow}
\end{figure*}