You're absolutely right, Heinera. I expected to see the graph as function of the angle between the measurement and the Z-axis.
So let's say Alice will measure every particle spin along the Z-axis.
What will Bobs measurements be along the horizontal plane? (perpendicular to the Z-axis)
Let's do a thought experiment.
A long time ago in a galaxy far far away, somebody used his entangled particle generator to create a gazillion pairs of entangled particles.
The first of each pair was shipped to Alice Alien, who lives several thousand light years away from us. My neighbour Bob...