# Trouble Making Ellipse Shaped Tikz Node

I have the following code where Im trying to draw a graph. I want the P and M nodes to be ellipses(oval shaped), but they just come out as circles. Im aware that an ellipse is a special case of a circle, but I don't know know how to specify the radii (writing ellipse(0.5 and 0.7) for instance didn't work).


\begin{tikzpicture}[node distance=2cm, minimum size = 1cm]

\node[rectangle,draw = black] (B) at (-1,4) {$B$};

\node[ellipse,draw = black] (M) at (-1,1) {$M$};

\node[ellipse,draw = black] (P) at (0.5,2.5) {$P$};

\node[diamond, draw = black] (U) at (1,5.5) {$U$};

\draw[->] (B) -- (M);

\draw[->] (B) -- (P);

\draw[->] (B) -- (U);

\draw[->] (M) -- (P);

\draw[->] (P) -- (U);

\end{tikzpicture} A circle is an ellipse, so your code is not wrong.
Nevertheless, if you want your node to be in ellipse shape, you can either insert a longer text in it (like "Power" in the example below), or ask your node to have a minimum width (like for the M node below).

(not related, but you didn't provide a Minimum Working Example, which is a better way to ask for answers)

\documentclass[tikz,border=3.14159mm]{standalone}
\usetikzlibrary{shapes}
\begin{document}

\begin{tikzpicture}[node distance=2cm, minimum size = 1cm]

\node[rectangle,draw = black] (B) at (-1,4) {$B$};
\node[ellipse, minimum width=2cm,draw = black] (M) at (-1,1) {$M$};
\node[ellipse,draw = black] (P) at (0.5,2.5) {$Power$};
\node[diamond, draw = black] (U) at (1,5.5) {$U$};

\draw[->] (B) -- (M);
\draw[->] (B) -- (P);
\draw[->] (B) -- (U);
\draw[->] (M) -- (P);
\draw[->] (P) -- (U);

\end{tikzpicture}

\end{document} 