\begin{tabular}{l*{6}{c}}
\hline
\addlinespace
                    &\multicolumn{1}{c}{\shortstack{ \\ Overall mean}}&\multicolumn{4}{c}{\shortstack{ \\ Difference in means:\\ Treatment $-$ control}}\\
                    &            &            &            &            &            \\
                    &\shortstack{Waves 1-3 \\ (1)}&\shortstack{Wave 1 \\ (2)}&\shortstack{P-value \\ (3)}&\shortstack{Waves 2-3 \\ (4)}&\shortstack{P-value \\ (5)}\\
\hline
\addlinespace
Female              &       0.613&     --0.043&        0.41&     --0.042&        0.20\\
                    &            &            &            &            &            \\
Age$^a$             &       33.51&      --0.47&        0.73&      --0.83&        0.42\\
                    &            &            &            &            &            \\
Student, full-time  &       0.569&     --0.089&        0.09&       0.004&        0.91\\
                    &            &            &            &            &            \\
Working, full- or part-time&       0.571&       0.141&        0.01&     --0.004&        0.91\\
                    &            &            &            &            &            \\
Married             &       0.272&       0.082&        0.08&     --0.004&        0.89\\
                    &            &            &            &            &            \\
Advanced degree$^b$ &       0.457&       0.045&        0.40&     --0.002&        0.94\\
                    &            &            &            &            &            \\
Household income$^a$&      55,139&       1,637&        0.74&     --4,399&        0.21\\
                    &            &            &            &            &            \\
Visits in the past 4 weeks, recorded&        6.91&        0.21&        0.74&      --0.10&        0.79\\
\hline
\addlinespace
N & 1,248 &  \multicolumn{2}{c}{\shortstack{166 control \\ 174 treated}}  & \multicolumn{2}{c}{\shortstack{456 control \\ 452 treated}} \\ 
\hline\hline
\end{tabular}
