Adding arrow to the middle of other arrow in LaTex?

Question

I would like to add an arrow from Variable 5 to the middle of the arrow that connects Variable 2 and Variable 3.

\documentclass[jou]{apa7}
\usepackage[american]{babel}
\usetikzlibrary{positioning}
\tikzset{mynode/.style={draw,text width=1.90cm,align=center}
}

\begin{document}

\begin{figure}
\begin{tikzpicture}
\node[mynode] (v1){Variable 1};
\node[mynode,below left=of v1](v2) {Variable 2};
\node[mynode,below right=of v1](v3) {Variable 3};
\node[mynode,below = 2.5cm of v1] (v4){Variable 4};
\node[mynode, above right=of v1](v5) {Variable 5};

\draw[-latex] (v2.north) -- node[auto,] {a} (v1.west);
\draw[-latex] (v1.east) -- node[auto,] {b} (v3.north);
\draw[-latex] (v2.east) -- node[below, align=center] {c} (v3.west);
\draw[-latex] (v2.south) -- node[below=3mm, align=center] {d} (v4.west);
\draw[-latex] (v3.south) -- node[below=3mm, align=center] {e} (v4.east);
\draw[-latex] (v5.south) -- node[auto,]{f} (v3.north);
\end{tikzpicture}
\end{figure}

\end{document}

Answer 1

You can use the calc library to calculate the middle between the nodes v2 and v3:

\documentclass[jou]{apa7}
\usepackage[american]{babel}
\usetikzlibrary{positioning}
\usetikzlibrary{calc}
\tikzset{mynode/.style={draw,text width=1.90cm,align=center}
}

\begin{document}

\begin{figure}
\begin{tikzpicture}
\node[mynode] (v1){Variable 1};
\node[mynode,below left=of v1](v2) {Variable 2};
\node[mynode,below right=of v1](v3) {Variable 3};
\node[mynode,below = 2.5cm of v1] (v4){Variable 4};
\node[mynode, above right=of v1](v5) {Variable 5};

\draw[-latex] (v2.north) -- node[auto,] {a} (v1.west);
\draw[-latex] (v1.east) -- node[auto,] {b} (v3.north);
\draw[-latex] (v2.east) -- node[below, align=center] {c} (v3.west);
\draw[-latex] (v2.south) -- node[below=3mm, align=center] {d} (v4.west);
\draw[-latex] (v3.south) -- node[below=3mm, align=center] {e} (v4.east);
\draw[-latex] (v5.south) -- node[auto,]{f} (v3.north);
\draw[-latex] (v5.south) -- ($(v2)!.5!(v3)$);
\end{tikzpicture}
\end{figure}

\end{document}