\begin{table}[htbp]\centering
\begin{threeparttable}
\caption{Robustness of the dispersion statistic (H1)}\label{tab:robust}
\small
\begin{tabular}{p{10cm}r}
\toprule
Specification & Median log gap \\
\midrule
Baseline median gap (A+B, storefront) & 0.154 \\
Balanced groups present in all 11 weeks (n groups 1300) & 0.163 \\
Unit-price normalisation & 0.154 \\
Trimmed 1/99\\% (mean, vs untrimmed mean) & 0.181 vs 0.189 \\
Cross-company group-weeks only & 0.183 \\
Non-promoted weeks only & 0.135 \\
Group-weeks with a promoted listing & 0.237 \\
Tiers A, price = p\_mode & 0.144 \\
Tiers A, price = p\_min & 0.143 \\
Tiers A, price = p\_max & 0.140 \\
Tiers A, price = p\_twmean & 0.138 \\
Tiers AB, price = p\_mode & 0.154 \\
Tiers AB, price = p\_min & 0.154 \\
Tiers AB, price = p\_max & 0.145 \\
Tiers AB, price = p\_twmean & 0.145 \\
Tiers ABC, price = p\_mode & 0.154 \\
Tiers ABC, price = p\_min & 0.154 \\
Tiers ABC, price = p\_max & 0.147 \\
Tiers ABC, price = p\_twmean & 0.145 \\
Tiers ABCD, price = p\_mode & 0.154 \\
Tiers ABCD, price = p\_min & 0.154 \\
Tiers ABCD, price = p\_max & 0.149 \\
Tiers ABCD, price = p\_twmean & 0.146 \\
Tiers AB, price = p\_mode+circulars & 0.154 \\
\bottomrule
\end{tabular}
\begin{tablenotes}[flushleft]\footnotesize
\item All rows use storefront listings in non-ambiguous group-weeks with $\ge$ 2 banners.
\end{tablenotes}
\end{threeparttable}
\end{table}