\documentclass{article}
\begin{document}
This specification uses {{val:sample_size|,.0f}} observations.
Mean income is {{mean_income|,.1f}}.

\begin{table}
\caption{Standard errors below estimates}
\label{tab:se_below}
\begin{tabular}{lccc}
Treatment & ### & ### & ### \\
          & ### & ### & ### \\
Controls  & ### & ### & ### \\
N         & #0,# & #0,# & #0,# \\
\end{tabular}
\end{table}

\begin{table}
\caption{Standard errors beside estimates}
\label{tab:inline_se}
\begin{tabular}{lccc}
Treatment & ### & ### & ### \\
Controls  & ### & ### & ### \\
N         & #0,# & #0,# & #0,# \\
\end{tabular}
\end{table}

\begin{table}
\caption{Ragged multicolumn header}
\label{tab:ragged}
\begin{tabular}{lcccc}
\multicolumn{3}{l}{Header A: #0,#} & \multicolumn{2}{r}{Header B: #0,#} \\
Row A & ### & ### & ### & ### \\
Row B & ### & ### & ### & ### \\
\end{tabular}
\end{table}
\end{document}
