\begin{table}%Tb1
\caption{\label{tab:stat}Predicted and simulated trigger chance.}
\small%\centering
\par
\begin{tabular}{llll}
\hline\hline\noalign{\smallskip}
STEC & ($N_2$,$N_3$,$N_4$) & Pred. chance & Sim. chance \\
\hline\noalign{\smallskip}
5 & (3, 5, 7) & $1.5\times 10^{-8}$ & $1.5\times 10^{-8}$ \\
10 & (5, 7, 11) & $3.6\times 10^{-8}$ & $3.8\times 10^{-8}$ \\
15 & (5, 9, 15) & $6.3\times 10^{-8}$ & $6.0\times 10^{-8}$ \\
\hline
\end{tabular}
\end{table}