\documentstyle[apjpt]{article}
\begin{document}

\label{taoxbins}
\begin{centering}
\begin{tabular}{clccc}
\multicolumn{4}{c}{ TABLE 2}  \\
\multicolumn{4}{c}{WOR REGRESSIONS of $\alpha_{ox}$(log$~l_{opt}$) }
\\ \hline \hline  
Bin Parameters & No. of Bins & Slope & Intercept  \\ \hline
 & & & \\  
\multicolumn{4}{c}{   Full LBQS/RASS Sample   } \\
% & & & \\  
$N_H$/log$~l_{opt}$ &  ~~~1/ 20 & 0.09$\pm$0.02 & $-1.4\pm$0.7  \\
$N_H$/log$~l_{opt}$ &  ~~~6/  7 & 0.07$\pm$0.02 & $-0.6\pm$0.5  \\ 
$N_H$/log$~l_{opt}$ &  ~~~5/  5 & 0.08$\pm$0.02 & $-0.9\pm$0.7  \\
$N_H$/log$~l_{opt}$ &  ~~~1/  5 & 0.11$\pm$0.03 & $-1.8\pm$0.9  \\
% & & & \\
$N_H$/Redshift &  ~~~1/ 17 & 0.11$\pm$0.01 & $-1.9\pm$0.4 \\
$N_H$/Redshift &  ~~~5/  5 & 0.11$\pm$0.02 & $-1.9\pm$0.7  \\
$N_H$/Redshift &  ~~~1/  4 & 0.15$\pm$0.01 & $-3.0\pm$0.2  \\

 & & & \\
\multicolumn{4}{c}{  Radio Quiet Sample   } \\
$N_H$/Redshift &  ~~~1/ 4 &0.15$\pm$0.07  &  $-3.1\pm$2.3  \\

 & & & \\
\multicolumn{4}{c}{   Radio Loud Sample    } \\
$N_H$/Redshift &  ~~~1/ 4 & $0.00\pm$0.26 & $1.5\pm$8.1 \\ \hline

\end{tabular}
\end{centering}

\end{document}