\begin{table}%t1
\caption{\label{tab:fitresults}Best-fit values for models $1$ and~$2$.}
\par
%\centering
\small
\begin{tabular}{r|cccc|c}  
\hline
\hline
&&&&& \\[-8pt]
\textbf{a)}\hspace{1.1cm} & $\Omega_{{\rm M}}$ & $\beta$ & \multicolumn{2}{c|}{$w_{{x}}= {\rm const.}$} & $\chi^2/n$ \\
\hline
&&&&& \\[-8pt]
            i) & $0.27^{\rm +0.02}_{-0.02}$ & $-$ & \multicolumn{2}{c|}{$-0.95^{\rm +0.08}_{-0.08}$} & 0.72 \\
Model $\;\;~1$& $0.24^{\rm +0.05}_{-0.04}$ & $-0.22^{\rm +0.38}_{-0.32}$ & \multicolumn{2}{c|}{$-1.18^{\rm +0.34}_{-0.34}$} & 0.71 \\
Model $2.1$    & $0.29^{\rm +0.05}_{-0.05}$ & $+0.08^{\rm +0.20}_{-0.40}$ & \multicolumn{2}{c|}{$-0.86^{\rm +0.24}_{-0.52}$} & 0.71 \\
Model $2.2$    & $0.24^{\rm +0.04}_{-0.03}$ & $-0.15^{\rm +0.15}_{-0.15}$ & \multicolumn{2}{c|}{$-1.16^{\rm +0.22}_{-0.22}$} & 0.71 \\
Model $2.3$    & $0.26^{\rm +0.02}_{-0.02}$ & $-0.10^{\rm +0.08}_{-0.08}$ & \multicolumn{2}{c|}{$-1.00^{\rm +0.12}_{-0.12}$} & 0.71 \\[2pt]
\hline
&&&&& \\[-8pt]
\textbf{b)}\hspace{1.1cm} & $\Omega_{{\rm M}}$ & $\beta$ & $w_0$ & $w_{{a}}$ & $\chi^2/n$ \\
\hline
&&&&& \\[-8pt]
            ii)& $0.28^{\rm +0.02}_{-0.02}$ & $-$ & $-1.14^{\rm +0.16}_{-0.08}$ & $0.88^{\rm +0.49}_{-0.49}$ & 0.71 \\
Model $\;\;~1$& $0.24^{\rm +0.04}_{-0.04}$ & $-0.24^{\rm +0.23}_{-0.23}$ & $-1.48^{\rm +0.38}_{-0.31}$ & $1.39^{\rm +0.40}_{-0.60}$ & 0.71 \\
Model $2.1$    & $0.23^{\rm +0.05}_{-0.05}$ & $-0.30^{\rm +0.31}_{-0.30}$ & $-1.65^{\rm +0.55}_{-0.47}$ & $1.72^{\rm +0.70}_{-1.03}$ & 0.71 \\
Model $2.2$    & $0.25^{\rm +0.03}_{-0.03}$ & $-0.13^{\rm +0.13}_{-0.13}$ & $-1.36^{\rm +0.24}_{-0.24}$ & $1.19^{\rm +0.51}_{-0.91}$ & 0.71 \\
Model $2.3$    & $0.26^{\rm +0.02}_{-0.02}$ & $-0.08^{\rm +0.08}_{-0.08}$ & $-1.21^{\rm +0.18}_{-0.18}$ & $0.91^{\rm +0.48}_{-1.09}$ & 0.71 \\[2pt]
\hline
\end{tabular}
\end{table}