Correlation to the Abbey pain score doesn't mean that much. The...

Correlation to the Abbey pain score doesn't mean that much. The Abbey pain score is prone to slight human error, and someone getting a 6/10 through ept vs 5/10 through Abbey does not mean much. It will through off a simple r^2 correlation.
What is interesting is the ability for someone without specific training in the Abbey pain assessment to use ept and get as good or potentially better accuracy then the Abbey test.
It is hard though, to quantify the actual accuracy of this tool as pain is subjective and we can only base it on the Abbey test.
It will only get better with time however, as more data and trails come in.
It's probably important to stress is that this is not an electronic version of the Abbey pain scale, and incorporates a lot more information to accurately rate pain.

Ri