Center the columns and, at the same time, apply equal width to them

Question

\documentclass[12pt]{article}
\usepackage[a4paper]{geometry}
\usepackage{booktabs}
\usepackage{threeparttable}
\usepackage{caption}
\usepackage{array}
\makeatletter
\g@addto@macro{\endtabular}{\rowfont{}}% Clear row font
\makeatother
\newcommand{\rowfonttype}{}% Current row font
\newcommand{\rowfont}[1]{% Set current row font
\gdef\rowfonttype{#1}#1%
}
\newcolumntype{L}{>{\rowfonttype}l}
\newcolumntype{C}{>{\rowfonttype}c}
\begin{document}
\begin{table}[h]
\begin{threeparttable}
    \footnotesize\caption{\footnotesize AAR,CAAR}
            \captionsetup{justification=justified, singlelinecheck=true}
    \begin{tabular}{C@{\hspace{1cm}}*{6}{p{.125\textwidth}}}
        \toprule
        & \multicolumn{2}{c}{Phase 1} &  \multicolumn{2}{c}{Phase 2} & \multicolumn{2}{c}{Phase 3} \\
        \cmidrule(lr){2-3}\cmidrule(lr){4-5}\cmidrule(lr){6-7}
        Day & AAR & CAAR &  AAR & CAAR & AAR & CAAR\\ 
        \midrule
        $-10$   & 0.00029 & 0.00029 & $-0.00077$ &  $-0.00077$& $-0.00116$ & $-0.00116$ \\
                & (0.09) &  (0.09) & $(-0.36)$ & $(-0.36)$&$(-0.42)$ &$ (-0.42)$
\bottomrule
    \end{tabular}
    \begin{tablenotes}[para]
        \item[*] $p<0.05$
        \item[**] $p<0.01$
        \item[***] $p<0.001$
    \end{tablenotes}
\end{threeparttable}
\end{table}
\end{document}

Hello,again!I am trying to center 6 right columns and have no clue where to put "C" in this expression :

\begin{tabular}{C@{\hspace{1cm}}*{6}{p{.125\textwidth}}}

I would appreciate any help!

Answer 1

Add >{\centering\arraybackslash} in font of the 6 last specifiers. However, the table is a little too wide for the text width, so I used a tabularx environment, which computes the width of the X columns, given the total width of the table.

\documentclass[12pt]{article}
\usepackage[a4paper,  showframe]{geometry}
\usepackage{booktabs}
\usepackage{threeparttable}
\usepackage{caption}
\usepackage{array,  tabularx}
\makeatletter
\g@addto@macro{\endtabular}{\rowfont{}}% Clear row font
\makeatother
\newcommand{\rowfonttype}{}% Current row font
\newcommand{\rowfont}[1]{% Set current row font
\gdef\rowfonttype{#1}#1%
}
\newcolumntype{L}{>{\rowfonttype}l}
\newcolumntype{C}{>{\rowfonttype}c}

\begin{document}

\begin{table}[!h]
\begin{threeparttable}
    \footnotesize\caption{\footnotesize AAR,CAAR}
            \captionsetup{justification=justified, singlelinecheck=true}
    \begin{tabularx}{\linewidth}{C@{\hspace{1cm}}*{6}{ >{\centering\arraybackslash}X}}
        \toprule
        & \multicolumn{2}{c}{Phase 1} & \multicolumn{2}{c}{Phase 2} & \multicolumn{2}{c}{Phase 3} \\
 \cmidrule(lr){2-3}\cmidrule(lr){4-5}\cmidrule(lr){6-7}
 Day & AAR & CAAR & AAR & CAAR & AAR & CAAR\\ \midrule $-10$ & 0.00029 & 0.00029 & $-0.00077$ & $-0.00077$& $-0.00116$ & $-0.00116$ \\
  & (0.09) & (0.09) & $(-0.36)$ & $(-0.36)$&$(-0.42)$ &$ (-0.42)$ \\
 \bottomrule
    \end{tabularx}
    \begin{tablenotes}[para]
\smallskip
        \item[*] $p<0.05$
        \item[**] $p<0.01$
        \item[***] $p<0.001$
    \end{tablenotes}
\end{threeparttable}
\end{table}

\end{document}