English: If ${\displaystyle \phi }$ is the angle between (the unit vectors) ${\displaystyle x}$ and ${\displaystyle y}$, then ${\displaystyle r^{2}=\cos ^{2}\phi }$ if ${\displaystyle \beta _{0}=0}$. The less perpendicular ${\displaystyle x}$ and ${\displaystyle y}$ are, the larger is the size of their sample correlation (${\displaystyle r}$) and the bigger is ${\displaystyle r^{2}}$. This figure is based on Hoornweg, Victor. 2018. Science: Under Submission. Hoornweg Press.