
\documentclass[a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{graphicx}
\usepackage{booktabs}
\usepackage{array}
\usepackage{paralist}
\usepackage{verbatim}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{setspace}
\onehalfspacing
\usepackage[parfill]{parskip}
\def\sym#1{\ifmmode^{#1}\else(^{#1})\fi}
\usepackage{siunitx} % for improved alignment of numbers in tables using the S type column
\usepackage{tabularx} % to make sure the table is as wide as the textwidth, for teh X type column
\usepackage{booktabs} % for horizontal lines with improved spacing
\usepackage{geometry} % for smaller margins, otherwise the table wouldn't fit
\usepackage{multirow} % for the multirow command
%--------------------------------------- Document --------------------------------------%
\begin{document}
\begin{table}[h]
\small
\setlength{\tabcolsep}{4pt}
\centering
\caption{ }
\begin{tabularx}{\linewidth}{@{}X
{3}{
S[table-format=4]
S[table-format=2.2]
S[table-format=2.2]
}
S[table-format=-1.3,
input-symbols = {()},
table-space-text-pre=),
table-space-text-post=\sym{},
table-align-text-post=false,
]@{}}
\toprule
\multicolumn{11}{@{}l@{}}{\textit{Panel A: }} \
\midrule
& \multicolumn{3}{c}{Overall} & \multicolumn{3}{c}{Set Household} & \multicolumn{3}{c}{Non-set Household} & \multicolumn{1}{l}{T-test}\
\cmidrule(r){2-4} \cmidrule(lr){5-7} \cmidrule(lr){8-10}
& {count} & {mean} & {sd} & {count} & {mean} & {sd} & {count} & {mean} &{sd} & \
\midrule
\multirow[t]{2}{=}{Average Age of the household respondent}
& 5000 & 44.7 & 12.8 & 3400 & 44.4 & 12.5 & 1016 & 44.9 & 13.1 & 0.511 \
& & & & & & & & & & (0.87) \
Percentage of Married
& 4000 & 0.86 & 0.35 & 345 & 0.87 & 0.34 & 800 & 0.85 & 0.35 & -0.014 \
& & & & & & & & & & {(}-0.88) \
\multirow[t]{2}{=}{Number of family that are dependent in the income}
& 99 & 0.83 & 0.67 & 94 & 0.79 & 0.70 & 5000 & 0.86 & 0.65 & 0.070\sym{*} \
& & & & & & & & & & (2.29) \
\midrule
\multicolumn{11}{@{}l@{}}{\textit{Panel B: }} \
\midrule
\midrule
\multicolumn{11}{@{}l@{}}{\textit{Panel C: }} \
\midrule
\bottomrule
\multicolumn{11}{@{}l@{}}{\footnotesize \textit{t} statistics in parentheses}\
\multicolumn{11}{@{}l@{}}{\footnotesize \sym{} (p<0.05), \sym{} (p<0.01), \sym{**} (p<0.001)}\
\end{tabularx}
\end{table}
\end{document}
Since you mentioned in the comments, that Panel B and Panel C will contain entries belonging to the same columns as the entries in panel A, I would suggest the following slightly different layout versions. In both, I have places "Panel A" belos the column headers in order to avoid repeating them for every panel. In order to visually separate them "Panel x" from the surrounding table, I have either used two horizontal lnes or a ombination of indentation and small vertical white space:

\documentclass[a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{graphicx}
\usepackage{booktabs}
\usepackage{array}
\usepackage{paralist}
\usepackage{verbatim}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{setspace}
\onehalfspacing
\usepackage[parfill]{parskip}
\def\sym#1{\ifmmode^{#1}\else(^{#1})\fi}
\usepackage{siunitx} % for improved alignment of numbers in tables using the S type column
\usepackage{tabularx} % to make sure the table is as wide as the textwidth, for teh X type column
\usepackage{booktabs} % for horizontal lines with improved spacing
\usepackage{geometry} % for smaller margins, otherwise the table wouldn't fit
\usepackage{multirow} % for the multirow command
%--------------------------------------- Document --------------------------------------%
\begin{document}
\begin{table}[h]
\small
\setlength{\tabcolsep}{4pt}
\centering
\caption{ }
\begin{tabularx}{\linewidth}{@{}X
{3}{
S[table-format=4]
S[table-format=2.2]
S[table-format=2.2]
}
S[table-format=-1.3,
input-symbols = {()},
table-space-text-pre=),
table-space-text-post=\sym{},
table-align-text-post=false,
]@{}}
\toprule
& \multicolumn{3}{c}{Overall} & \multicolumn{3}{c}{Set Household} & \multicolumn{3}{c}{Non-set Household} & \multicolumn{1}{l}{T-test}\
\cmidrule(r){2-4} \cmidrule(lr){5-7} \cmidrule(lr){8-10}
& {count} & {mean} & {sd} & {count} & {mean} & {sd} & {count} & {mean} &{sd} & \
\midrule
\multicolumn{11}{@{}l@{}}{\textit{Panel A: }} \
\midrule
\multirow[t]{2}{=}{Average Age of the household respondent}
& 5000 & 44.7 & 12.8 & 3400 & 44.4 & 12.5 & 1016 & 44.9 & 13.1 & 0.511 \
& & & & & & & & & & (0.87) \
Percentage of Married
& 4000 & 0.86 & 0.35 & 345 & 0.87 & 0.34 & 800 & 0.85 & 0.35 & -0.014 \
& & & & & & & & & & {(}-0.88) \
\multirow[t]{2}{=}{Number of family that are dependent in the income}
& 99 & 0.83 & 0.67 & 94 & 0.79 & 0.70 & 5000 & 0.86 & 0.65 & 0.070\sym{} \
& & & & & & & & & & (2.29) \
\midrule
\multicolumn{11}{@{}l@{}}{\textit{Panel B: }} \
\midrule
\multirow[t]{2}{=}{Average Age of the household respondent}
& 5000 & 44.7 & 12.8 & 3400 & 44.4 & 12.5 & 1016 & 44.9 & 13.1 & 0.511 \
& & & & & & & & & & (0.87) \
Percentage of Married
& 4000 & 0.86 & 0.35 & 345 & 0.87 & 0.34 & 800 & 0.85 & 0.35 & -0.014 \
& & & & & & & & & & {(}-0.88) \
\midrule
\multicolumn{11}{@{}l@{}}{\textit{Panel C: }} \
\midrule
\multirow[t]{2}{=}{Average Age of the household respondent}
& 5000 & 44.7 & 12.8 & 3400 & 44.4 & 12.5 & 1016 & 44.9 & 13.1 & 0.511 \
& & & & & & & & & & (0.87) \
Percentage of Married
& 4000 & 0.86 & 0.35 & 345 & 0.87 & 0.34 & 800 & 0.85 & 0.35 & -0.014 \
& & & & & & & & & & {(}-0.88) \
\bottomrule
\multicolumn{11}{@{}l@{}}{\footnotesize \textit{t} statistics in parentheses}\
\multicolumn{11}{@{}l@{}}{\footnotesize \sym{} (p<0.05), \sym{} (p<0.01), \sym{*} (p<0.001)}\
\end{tabularx}
\end{table}
\begin{table}[h]
\small
\setlength{\tabcolsep}{3.5pt}
\centering
\caption{ }
\begin{tabularx}{\linewidth}{X
{3}{
S[table-format=4]
S[table-format=2.2]
S[table-format=2.2]
}
S[table-format=-1.3,
input-symbols = {()},
table-space-text-pre=),
table-space-text-post=\sym{},
table-align-text-post=false,
]@{}}
\toprule
& \multicolumn{3}{c}{Overall} & \multicolumn{3}{c}{Set Household} & \multicolumn{3}{c}{Non-set Household} & \multicolumn{1}{l}{T-test}\
\cmidrule(r){2-4} \cmidrule(lr){5-7} \cmidrule(lr){8-10}
& {count} & {mean} & {sd} & {count} & {mean} & {sd} & {count} & {mean} &{sd} & \
\midrule
\multicolumn{11}{@{}l@{}}{\textit{Panel A: }} \
\addlinespace
\multirow[t]{2}{=}{Average Age of the household respondent}
& 5000 & 44.7 & 12.8 & 3400 & 44.4 & 12.5 & 1016 & 44.9 & 13.1 & 0.511 \
& & & & & & & & & & (0.87) \
Percentage of Married
& 4000 & 0.86 & 0.35 & 345 & 0.87 & 0.34 & 800 & 0.85 & 0.35 & -0.014 \
& & & & & & & & & & {(}-0.88) \
\multirow[t]{2}{=}{Number of family that are dependent in the income}
& 99 & 0.83 & 0.67 & 94 & 0.79 & 0.70 & 5000 & 0.86 & 0.65 & 0.070\sym{} \
& & & & & & & & & & (2.29) \
\midrule
\multicolumn{11}{@{}l@{}}{\textit{Panel B: }} \
\addlinespace
\multirow[t]{2}{=}{Average Age of the household respondent}
& 5000 & 44.7 & 12.8 & 3400 & 44.4 & 12.5 & 1016 & 44.9 & 13.1 & 0.511 \
& & & & & & & & & & (0.87) \
Percentage of Married
& 4000 & 0.86 & 0.35 & 345 & 0.87 & 0.34 & 800 & 0.85 & 0.35 & -0.014 \
& & & & & & & & & & {(}-0.88) \
\midrule
\multicolumn{11}{@{}l@{}}{\textit{Panel C: }} \
\addlinespace
\multirow[t]{2}{=}{Average Age of the household respondent}
& 5000 & 44.7 & 12.8 & 3400 & 44.4 & 12.5 & 1016 & 44.9 & 13.1 & 0.511 \
& & & & & & & & & & (0.87) \
Percentage of Married
& 4000 & 0.86 & 0.35 & 345 & 0.87 & 0.34 & 800 & 0.85 & 0.35 & -0.014 \
& & & & & & & & & & {(}-0.88) \
\bottomrule
\multicolumn{11}{@{}l@{}}{\footnotesize \textit{t} statistics in parentheses}\
\multicolumn{11}{@{}l@{}}{\footnotesize \sym{} (p<0.05), \sym{} (p<0.01), \sym{*} (p<0.001)}\
\end{tabularx}
\end{table}
\end{document}