\begin{tabular}{lrrrrrrrrrrr}
\toprule
\multicolumn{2}{c}{Design} & \multicolumn{5}{c}{GMD} & \multicolumn{5}{c}{Third L-moment} \\
\cmidrule(lr){1-2}\cmidrule(lr){3-7}\cmidrule(lr){8-12}
$(G_n,m_n^2/n)$ & $\rho$ & $\frac{\mathrm{MAD}}{\mathrm{IQR}}$ & $\frac{\mathrm{SE}}{\mathrm{SD}}_{\mathrm{rob}}$ & 5\%$_{\mathrm{rob}}$ & $\frac{\mathrm{SE}}{\mathrm{SD}}_{\mathrm{iid}}$ & 5\%$_{\mathrm{iid}}$ & $\frac{\mathrm{MAD}}{\mathrm{IQR}}$ & $\frac{\mathrm{SE}}{\mathrm{SD}}_{\mathrm{rob}}$ & 5\%$_{\mathrm{rob}}$ & $\frac{\mathrm{SE}}{\mathrm{SD}}_{\mathrm{iid}}$ & 5\%$_{\mathrm{iid}}$ \\
\midrule
$(200,0.097)$ & 0.00 & 0.036 & 0.973 & 0.076 & 0.975 & 0.075 & 0.014 & 0.952 & 0.098 & 0.954 & 0.097 \\
 & 0.25 & 0.042 & 0.929 & 0.091 & 0.867 & 0.104 & 0.016 & 0.900 & 0.118 & 0.875 & 0.117 \\
 & 0.50 & 0.046 & 0.965 & 0.081 & 0.792 & 0.133 & 0.016 & 0.912 & 0.108 & 0.808 & 0.135 \\
\midrule
$(400,0.070)$ & 0.00 & 0.026 & 0.992 & 0.051 & 0.995 & 0.051 & 0.010 & 0.983 & 0.066 & 0.986 & 0.065 \\
 & 0.25 & 0.027 & 0.950 & 0.074 & 0.869 & 0.100 & 0.010 & 0.943 & 0.086 & 0.907 & 0.091 \\
 & 0.50 & 0.032 & 0.965 & 0.079 & 0.754 & 0.145 & 0.012 & 0.958 & 0.089 & 0.816 & 0.129 \\
\midrule
$(600,0.054)$ & 0.00 & 0.019 & 1.019 & 0.054 & 1.020 & 0.054 & 0.007 & 1.016 & 0.063 & 1.018 & 0.064 \\
 & 0.25 & 0.022 & 0.981 & 0.058 & 0.888 & 0.083 & 0.008 & 0.969 & 0.066 & 0.923 & 0.075 \\
 & 0.50 & 0.026 & 0.965 & 0.064 & 0.738 & 0.155 & 0.010 & 0.945 & 0.081 & 0.790 & 0.132 \\
\bottomrule
\end{tabular}
