Man, you're testing me.
The thing is, you CAN'T observe that effect, because there IS no point of origin. If there was one, then it would be true, but because there is none, you just can't. You are trying to observe movement away from a point that doesn't exist.
If there is no point of origin, then we are not expanding and the big bang is false. The Big bang itself says we were once smaller and that means we are moving away from where we were.
You yourself were once smaller. Can you point to any one cell in your body that is the center of you, from which you expanded?
I don't understand your "data set is too small" point. We've got data from galaxies as far as +10 billion light years away from us, nerly from the edge of the observable universe. What more data you can ask for?
But they wouldn't move in any other way than radially. Their position on the sky wouldn't change. I could draw more points and more lines on that picture, and they would all follow the same set of rules. Their movement would be proportional to their distance from you, and it'd look like they're receeding from you, regardless of which point you're standing at.
But at different speeds away from you... if they were radial, the shifts would be the same, but then the whole idea that Andromeda sees the same radial expansion would mean that stars would collide due to all the galaxies expanding away from each other. It can't be radial expansion for every point within. Not if it stays consistent in the sky. If the expansion was radial, it would appear to shift in the sky depending on which star you were on. In order for that to work, everything would have to expand away from each other at different speeds and that should be measurable.
They do move at different speeds. The farther something is, the higher the speed(there is more space to expand).
I completely fail to follow the conclusion of stars colliding.
And as I said, all you need to do to test that it works, and produce the results we postulated it should produce, is to play with the cartesian coordinate system.
In the pictures that Il Palazzo provided earlier, the redshifts should be different between D1 and D2 (and D3, but that should be "closer" do D1 than D2 is. D2 is inherently growing slower than D1 and D3 by simple geometry.)
They are different. The point at the end of D1 is farther away than the one at the end of D2, so it got redshifted more(there was more space created between).
This is measurable, and it's exactly the basis of the expanding universe theory. It shows that everything is receeding away from you(the observer).