\documentclass[border=0cm]{standalone}

\usepackage{tikz}
\usepackage{pgfplots}
\usepackage{bm}

\definecolor{gmlm}{RGB}{0,0,0}
\definecolor{tsir}{RGB}{255,50,50}

\pgfplotsset{
    compat=newest,
    every axis/.style={
        grid=both,
        grid style={gray, dotted},
        label style={font=\tiny},
        tick label style={font=\tiny}
    },
    % every axis plot/.append style={
    %     mark = *,
    %     mark size = 1pt,
    %     line width=0.8pt
    % }
}
\tikzset{
    legend entry/.style={
        mark = *,
        mark size = 1pt,
        mark indices = {2},
        line width=0.8pt
    }
}

\begin{document}
\begin{tikzpicture}[>=latex]

    \begin{axis}[
        name=p1, % ymin = -60, ymax = 60
        width=7.5cm, height=5cm,
        xticklabel=\empty
    ]
        \addplot[color = tsir] table[x = time, y = tsir.reg.beta] {tsir-vs-gmlm-1.csv};
        \addplot[color = gmlm] table[x = time, y = gmlm.beta] {tsir-vs-gmlm-1.csv};
    \end{axis}
    \node[anchor = base west, yshift = 0.3em] at (p1.north west) {
        Time
    };
    \node[anchor = south, xshift = -1.5em, rotate = 90] at (p1.west) {
        $\widehat{\beta}_1$
    };

    \begin{axis}[
        name=p2,
        width=7.5cm, height=5cm,
        anchor=north west, at={(p1.below south west)}, yshift=0.4em
    ]
        \addplot[color = tsir] table[x = time, y = tsir.reg.Gamma] {tsir-vs-gmlm-1.csv};
        \addplot[color = gmlm] table[x = time, y = gmlm.Gamma] {tsir-vs-gmlm-1.csv};
    \end{axis}
    \node[anchor = south, xshift = -1.5em, rotate = 90] at (p2.west) {
        $\widehat{\Gamma}_1$
    };
    \node[anchor = north, yshift = -1em] at (p2.south) {
        Time [s]
    };

    \begin{axis}[
        name=p3,
        width=7.5cm, height=5cm,
        anchor=north west, at={(p1.right of north east)}, xshift=1cm,
        xticklabel=\empty
    ]
        \addplot[color = gmlm, dotted, mark = *, mark size = 1pt] table[x = sensor, y = gmlm.beta] {tsir-vs-gmlm-2.csv};
        \addplot[color = tsir, dotted, mark = *, mark size = 1pt] table[x = sensor, y = tsir.reg.beta] {tsir-vs-gmlm-2.csv};
    \end{axis}
    \node[anchor = base west, yshift = 0.3em] at (p3.north west) {
        Sensors
    };
    \node[anchor = south, xshift = -1em, rotate = 90] at (p3.west) {
        $\widehat{\beta}_2$
    };

    \begin{axis}[
        name=p4,
        width=7.5cm, height=5cm,
        anchor=north west, at={(p3.below south west)}, yshift=0.4em
    ]
        \addplot[color = gmlm, dotted, mark = *, mark size = 1pt] table[x = sensor, y = gmlm.Gamma] {tsir-vs-gmlm-2.csv};
        \addplot[color = tsir, dotted, mark = *, mark size = 1pt] table[x = sensor, y = tsir.reg.Gamma] {tsir-vs-gmlm-2.csv};
    \end{axis}
    \node[anchor = south, xshift = -1em, rotate = 90] at (p4.west) {
        $\widehat{\Gamma}_2$
    };
    \node[anchor = north, yshift = -1em] at (p4.south) {
        Sensor Index
    };

\end{tikzpicture}
\end{document}