# How to place a line for “N.A.” at a cell of a table

I see some tables with a horizontal line placed at the middle of a cell, for terms not available or not applicable. For example, how shall I replace the "N.A." below with such a line?

\begin{table}[htbp]
\centering
\caption{Caption}
\begin{tabular}{ccc}
\hline
Auctions of & P\_value &  $\widehat{\theta}$ \\
\midrule
2  & 0.375 & $\underset{(0.230)}{0.354}$ \\
3  & 0.002 & N.A. \\
\bottomrule
\end{tabular}
\end{table}

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Is \--- enough? Or maybe \-- or even \verb+-+. –  Sigur May 16 at 23:33
@Sigur \--- and \--? Did you mean --- and --? –  egreg May 17 at 8:09
@egreg, I always had used that. What is the difference? Non breakable? –  Sigur May 17 at 15:56
@Sigur \- gives a discretionary hyphen, so \--- is a discretionary hyphen followed by an en-dash. –  egreg May 17 at 16:56
@Sigur I don't understand what you're saying; \- is a control symbol, so it's already a complete control sequence name; \--- is three tokens: \-, - and -; unless you change the definition of \-, \- is a discretionary hyphen and, at typesetting time, -- is converted to an en-dash. –  egreg May 17 at 17:06

I suggest defining a command \NA that holds an em-dash ---:

\documentclass{article}
\usepackage{booktabs,amsmath}
\newcommand{\NA}{---}
\begin{document}

\begin{tabular}{ccc}
\toprule
Auctions of & \detokenize{P_value} &  $\widehat{\theta}$ \\
\midrule
2  & 0.375 & $\underset{(0.230)}{0.354}$ \\
3  & 0.002 & \NA \\
\bottomrule
\end{tabular}

\end{document}


This way, if you don't like it later (in life), just change the definition to something more suitable (perhaps an en-dash --).

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