My answer to your question is at the bottom, but it needs some explaining before I get there.
I feel like this question is saying "We have a site that this question would fit on, but..."
- "but it is relevant to us also"
- or "but we will have a different view point then them"
If the question could be asked on another site and get a good answer there, then it should be there an not here. However, it is true that many times you can get a better explanation from someone in the same field as you. The reason for this is that someone in the same field as you is able to give examples that are relevant to you. For that reason, if the question can be asked specific enough to signal processing, then by all means ask it here. However, if the question is too broad then this is not the best place for it.
So to your specific example of statistical significance of mean squared coherence values, tie the question back to what this means for a signal processing person and I think it would be on-topic.