\documentclass{article}

\usepackage{amsmath}

\begin{document}

\begin{figure}
  \setlength{\unitlength}{1.0mm}
  \begin{picture}(120,80)(-10,-40)
    \put(-3,1){\mbox{$\boldsymbol\mu$}}
    \put(0,-35){\line(0,1){70}}
    \put(-10,0){\line(1,0){120}}
    \put(0,0){\circle*{1}}
    \put(80,0){\circle*{1}}
    \put(60,0){\circle*{1}}
    \put(100,0){\circle*{1}}
    \put(80,20){\circle*{1}}
    \put(80,-20){\circle*{1}}
    \put(80,1){\mbox{$\boldsymbol\theta$}}
    \put(60,1){\mbox {$\mathbf X_1$}}
    \put(100,1){\mbox {$\mathbf X_3$}}
    \put(80,21){\mbox {$\mathbf X_2$}}
    \put(80,-19){\mbox {$\mathbf X_4$}}
    \thicklines
    \put(60,0){\vector(-1,0){8.3}}
    \put(100,0){\vector(-1,0){5}}
    \put(80,20){\vector(-4,-1){5.9}}
    \put(80,-20){\vector(-4,1){5.9}}
    \thinlines
  \end{picture}
  \caption{Shrinkage estimators}
  \label{fig:shrinkage}
\end{figure}

\end{document}

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