This problem is not from a textbook. This one is made up. Some are from textbooks, but a lot of them are from research studies that I have adapted into examples.
Does it matter how I look at the claim. What if instead I did before < after. Then my Hnull would be >/= and HA is 0 does it mean there is a difference?
Yes and no. You can write your claim either way, but you need to match the subtraction you perform to the order implied by the claim. If you write before < after, that leads to before - after < 0. Notice, that the before - after implies you must subtract the after row from the before row. If you do that, everything will be equivalent.
Which book do you use to get the examples from?
This problem is not from a textbook. This one is made up. Some are from textbooks, but a lot of them are from research studies that I have adapted into examples.
Does it matter how I look at the claim. What if instead I did before < after. Then my Hnull would be >/= and HA is 0 does it mean there is a difference?
Yes and no. You can write your claim either way, but you need to match the subtraction you perform to the order implied by the claim. If you write before < after, that leads to before - after < 0. Notice, that the before - after implies you must subtract the after row from the before row. If you do that, everything will be equivalent.