1\begin{table}[htbp]\centering2\begin{threeparttable}3\caption{Robustness of the dispersion statistic (H1)}\label{tab:robust}4\small5\begin{tabular}{p{10cm}r}6\toprule7Specification & Median log gap \\8\midrule9Baseline median gap (A+B, storefront) & 0.154 \\10Balanced groups present in all 11 weeks (n groups 1300) & 0.163 \\11Unit-price normalisation & 0.154 \\12Trimmed 1/99\\% (mean, vs untrimmed mean) & 0.181 vs 0.189 \\13Cross-company group-weeks only & 0.183 \\14Non-promoted weeks only & 0.135 \\15Group-weeks with a promoted listing & 0.237 \\16Tiers A, price = p\_mode & 0.144 \\17Tiers A, price = p\_min & 0.143 \\18Tiers A, price = p\_max & 0.140 \\19Tiers A, price = p\_twmean & 0.138 \\20Tiers AB, price = p\_mode & 0.154 \\21Tiers AB, price = p\_min & 0.154 \\22Tiers AB, price = p\_max & 0.145 \\23Tiers AB, price = p\_twmean & 0.145 \\24Tiers ABC, price = p\_mode & 0.154 \\25Tiers ABC, price = p\_min & 0.154 \\26Tiers ABC, price = p\_max & 0.147 \\27Tiers ABC, price = p\_twmean & 0.145 \\28Tiers ABCD, price = p\_mode & 0.154 \\29Tiers ABCD, price = p\_min & 0.154 \\30Tiers ABCD, price = p\_max & 0.149 \\31Tiers ABCD, price = p\_twmean & 0.146 \\32Tiers AB, price = p\_mode+circulars & 0.154 \\33\bottomrule34\end{tabular}35\begin{tablenotes}[flushleft]\footnotesize36\item All rows use storefront listings in non-ambiguous group-weeks with $\ge$ 2 banners.37\end{tablenotes}38\end{threeparttable}39\end{table}40