\begin{table}%t4 
\caption{Fitted age-velocity dispersion relations.} \label{heatlaw}  
%\centering
\par
\begin{tabular}{lcccccccc} 
\hline  \hline 
   Parametrization & Binned & Age & $\vert W\vert$ & $x_{\rm tot}$ & $x_u$ & $x_v$ & $x_w$  & note \\ 
                         & by & calibration & weight &  &  &  &  & \\ 
\hline 
$\sigma\propto (1+t/\tau)^x$ & Number & RPM98 & No & $0.27\pm 0.01$ & $0.24\pm 0.02$ & $0.30\pm 0.03$ & $0.34\pm 0.02$ & \\ 
$\sigma\propto (1+t/\tau)^x$ & Number & RPM98 & Yes & $0.50\pm 0.02$& $0.47\pm 0.02$ & $0.57\pm 0.04$ & $0.46\pm 0.03$ & \\ 
$\sigma\propto t^x$         & Age    & RPM98 & No & $0.42\pm 0.04$ & $0.40\pm 0.02$ & $0.48\pm 0.04$ & $0.41\pm 0.03$ & \\ 
$\sigma\propto t^x$         & Number & RPM98 & No & $0.26\pm 0.03$ & $0.23\pm 0.04$ & $0.28\pm 0.04$ & $0.35\pm 0.06$ & \\ 
$\sigma\propto t^x$         & Number & Donahue (1998) & No & $0.33\pm 0.05$ & $0.29\pm 0.05$ & $0.39\pm 0.05$ & $0.37\pm 0.08$ & \\  
$\sigma\propto t^x$         & Number & Donahue (1998) & Yes & $0.50\pm 0.08$ & $0.36\pm 0.09$ & $0.49\pm 0.13$ & $0.53\pm 0.07$ & \\ 
$\sigma = a_0 + a_1 t^x$    & Number & RPM98 & No & $0.24\pm 0.04$ & $0.23\pm 0.04$ & $0.37\pm 0.07$ & $0.30\pm 0.09$ & \\ 
$\sigma\propto t^x$         & Age    & RPM98 & Yes & $0.24\pm 0.06$ & $0.24\pm 0.07$ & $0.19\pm 0.05$ & $0.25\pm 0.03$ & $p_{\rm II} < 0.75$ \\ 
$\sigma\propto t^x$         & Age    & RPM98 & No & $0.24\pm 0.04$ & $0.25\pm 0.06$ & $0.28\pm 0.04$ & $0.25\pm 0.03$ & $p_{\rm II} < 0.75$ \\ 
\hline 
\end{tabular} 
\end{table}