Changing caption setup font family in tables.

Question

I would like to change the caption font family to ptm. I am using metropolis template for beamer.

Is there any way to change the caption to ptm font family?

\documentclass{beamer}
\usetheme{metropolis}
\usepackage{ragged2e}
\usepackage{tikz}
\usepackage{caption}
\captionsetup[table]{skip=1pt}
\usetikzlibrary{positioning}
\usepackage[flushleft]{threeparttable}
\begin{document}
\begin{frame}{Results: DiD - Development Policy}
\begin{table}[H]
\centering
    {
        \fontencoding{T1}\fontfamily{ptm}\selectfont
        \scalebox{0.8}{ 
            \begin{threeparttable}
                \caption{\textsc{Reduced-Form Models for Log of Income for Self-Employed Workers}}
                \label{table2}
                \begin{tabular}{@{}p{5cm} cccc}
                    \toprule \toprule
                    & \multicolumn{4}{c}{Model}                                                                 \\ \cmidrule{2-5} 
                    Variables                           & (i)                  & (ii)                 & (iii)                & (iv)                 \\ \midrule
                    Time                                & 0.34***              & 0.35***              & 0.22***              & 0.30***              \\
                    & (0.03)               & (0.03)               & (0.06)               & (0.05)               \\
                    Treatment                           & -0.03                & 0.03                 & -0.07                & -0.06                \\
                    & (0.05)               & (0.04)               & (0.06)               & (0.05)               \\
                    Time $\cdot$ Treatment              &  0.08                & 0.13**               & 0.20**               & 0.21***              \\
                    & (0.07)               & (0.06)               & (0.08)               & (0.07)               \\
                    Matched                             &  No                  & No                   & Yes                  & Yes                  \\
                    Controls                            &  No                  & Yes                  & No                   & Yes                  \\
                    Standard error of the regression    &  1.170               & 1.033                & 1.067                & 0.937                \\
                    Observations                        &  8,085               & 8,085                & 2,584                & 2,584                \\ \bottomrule
                \end{tabular}
                \begin{tablenotes}[flushleft]
                    \small
                    \item \textit{Notes}: Standard errors are shown in parentheses. Statistical significance at the 1, 5 and 10\% levels is indicated by ***,** and *, respectively.
                \end{tablenotes}
            \end{threeparttable}
        }
    }
\end{table}
\end{frame}
\end{document}

This is my result:

Answer 1

I found two solutions. One is to set \captionfont directly. The other is to set the default caption font using \setbeamerfont{caption}{...}.

Note: threeepartable does not have to be inside a table environment.

\documentclass{beamer}
\usetheme{metropolis}
\usepackage{ragged2e}
%\usepackage{tikz}% redundant
\usepackage{caption}
\captionsetup[table]{skip=1pt}%
\usetikzlibrary{positioning}
\usepackage[flushleft]{threeparttable}
\usepackage{booktabs}

\setbeamerfont*{caption}{family=\fontfamily{ptm}}

\begin{document}
\makeatletter
\begin{frame}{Results: DiD - Development Policy}
    \centering
        \fontencoding{T1}\fontfamily{ptm}\selectfont
        \scalebox{0.8}{\textsc{Reduced-Form Models for Log of Income for}} %comparison
        \scalebox{0.8}{%
            \begin{threeparttable}
                %\def\captionfont{\fontfamily{ptm}}%
                \caption{\textsc{Reduced-Form Models for Log of Income for Self-Employed Workers}}
                \label{table2}
                \begin{tabular}{@{}p{5cm} cccc}
                    \toprule \toprule
                    & \multicolumn{4}{c}{Model}                                                                 \\ \cmidrule{2-5} 
                    Variables                           & (i)                  & (ii)                 & (iii)                & (iv)                 \\ \midrule
                    Time                                & 0.34***              & 0.35***              & 0.22***              & 0.30***              \\
                    & (0.03)               & (0.03)               & (0.06)               & (0.05)               \\
                    Treatment                           & -0.03                & 0.03                 & -0.07                & -0.06                \\
                    & (0.05)               & (0.04)               & (0.06)               & (0.05)               \\
                    Time $\cdot$ Treatment              &  0.08                & 0.13**               & 0.20**               & 0.21***              \\
                    & (0.07)               & (0.06)               & (0.08)               & (0.07)               \\
                    Matched                             &  No                  & No                   & Yes                  & Yes                  \\
                    Controls                            &  No                  & Yes                  & No                   & Yes                  \\
                    Standard error of the regression    &  1.170               & 1.033                & 1.067                & 0.937                \\
                    Observations                        &  8,085               & 8,085                & 2,584                & 2,584                \\ \bottomrule
                \end{tabular}
                \begin{tablenotes}[flushleft]
                    \small
                    \item \textit{Notes}: Standard errors are shown in parentheses. Statistical significance at the 1, 5 and 10\% levels is indicated by ***,** and *, respectively.
                \end{tablenotes}
            \end{threeparttable}
}
\end{frame}
\end{document}