\begin{tabular}{lrrrr}
\toprule
variant & $c$ & $b$ & $D^\ast$ & $R^2$ \\
\midrule
terminal-only ($\alpha=0$) & 0.8272 & 0.0350 & 0.2028 & 0.938 \\
original & 0.5792 & 0.0412 & 0.0978 & 0.784 \\
arrival ($\lambda_h=0$) & 0.4076 & 0.0282 & 0.0475 & 0.603 \\
arrival+hold ($\lambda_h=1$) & 0.4079 & 0.0214 & 0.0362 & 0.625 \\
\textbf{arrival+hold} ($\lambda_h=0.5$) & 0.3919 & 0.0241 & 0.0397 & 0.616 \\
\bottomrule
\end{tabular}