I understand the difference between NAGE and Off-topic, and I notice it has already been pointed out that many people do not, and vote randomly one or the other option. Fine.
There are lengthy answers explaining the difference. Fine.
Still, fact is most people won't bother and just keep on voting randomly. I suggest to actually change the name of these options, such as:
- Related, but off-topic
- Completely unrelated
And inserting a popup message when you onhover it which explains that "questions that are unrelated to that site, so much that we have no reason to expect them to be asked here rather then on any other random site, fall back in the third and not in the second category".