\begin{table}[t!]
\begin{center}
\begin{threeparttable}
\begin{scriptsize}
\caption{Estimation strategy: First-stage estimates\label{EEREV-D-21-00004_Table3}}
\begin{tabular*}{\columnwidth}{@{\extracolsep{\stretch{1}}}l*{5}{c}@{}}
\hline
\hline
&\multicolumn{1}{c}{(1)} &\multicolumn{1}{c}{(2)}  &\multicolumn{1}{c}{(3)} &\multicolumn{1}{c}{(4)} &\multicolumn{1}{c}{(5)}\\
\cmidrule(lr){2-6}
\multicolumn{1}{l}{\textit{Specification}}&\multicolumn{1}{c}{No controls} &\multicolumn{1}{c}{Fertility}  &\multicolumn{1}{c}{Lat-lon poly} &\multicolumn{1}{c}{Historical} &\multicolumn{1}{c}{Historical and}\\
 &\multicolumn{1}{c}{} &\multicolumn{1}{c}{controls}  &\multicolumn{1}{c}{and dialect} &\multicolumn{1}{c}{controls} &\multicolumn{1}{c}{contemporary}\\
\cmidrule(lr){2-6}
& \multicolumn{5}{c}{First-Stage Estimates. Dep. Variable: Conscription proxy (\%)}\\
\hline
\\ Eligible births (\%)&       0.372***&       0.475***&       0.357***&       0.261***&       0.240***\\
                    &     (0.033)   &     (0.045)   &     (0.048)   &     (0.050)   &     (0.054)   \\
[0.3em] Born 1903-1912 (\%)&               &     --0.019   &     --0.046   &     --0.011   &     --0.007   \\
                    &               &     (0.064)   &     (0.058)   &     (0.056)   &     (0.056)   \\
[0.3em] Born 1913-1922 (\%)&               &     --0.299** &     --0.198   &     --0.147   &     --0.126   \\
                    &               &     (0.146)   &     (0.169)   &     (0.165)   &     (0.160)   \\
[0.3em] Born 1923-1932 (\%)&               &     --0.310***&     --0.188   &     --0.114   &     --0.099   \\
                    &               &     (0.113)   &     (0.128)   &     (0.126)   &     (0.135)   \\
\\ First-stage $ F $-statistic&      129.04   &      110.64   &       55.53   &       27.37   &       19.95   \\
\\ Lat-lon polynomial &  &  & 2nd & 2nd & 2nd \\ 
Border segment FE   &               &               &         Yes   &         Yes   &         Yes   \\
Historical dialect FE &               &               &         Yes   &         Yes   &         Yes   \\
Historical controls &               &               &               &         Yes   &         Yes   \\
Contemporary controls (1965) &               &               &               &               &         Yes   \\
\hline
Mean dep. variable  &        7.74   &        7.74   &        7.74   &        7.74   &        7.74   \\
Observations        &         462   &         462   &         462   &         462   &         462   \\
Clusters            &          32   &          32   &          32   &          32   &          32   \\
\hline
\hline
\end{tabular*}
\end{scriptsize}
\begin{tablenotes}[normal,flushleft]
\begin{scriptsize}
\item \emph{Notes}:
First-stage estimates of the effect of the draft rule on Wehrmacht conscription. 
The unit of observation is a municipality. 
Standard errors clustered at the canton level in parentheses. 
Columns (3) to (5) include a quadratic polynomial in latitude and longitude ($ x+y+x^2+y^2+xy $). 
First-stage F-statistic is the Kleibergen-Paap rk Wald F-statistic. 
* significant at 10\%; ** at 5\%; *** at 1\%. 
\end{scriptsize}
\end{tablenotes}
\end{threeparttable}
\end{center}
\end{table}
