Personal opinion - it can never be measured accurately because it's perceptional. Pain and pleasure can be the same thing, it's hard to quantify because it exi

Personal opinion - it can never be measured accurately because it's perceptional. Pain and pleasure can be the same thing, it's hard to quantify because it exists at different points of the same spectrum, and cell damage isn't necessarily an indicator either (papercut painful but same cut during gardening not noticed). Environmental and third party factors also conflate results, air pressure on tooth ache, acupuncture or different pain to relieve pain elsewhere, distractions, and endorphin hits from it being long running pain (you get used to it). So yes electrical activity may be similar, but the way in which it's finally perceived is what you want to actually measure. To do that I believe the only way to measure it is the 1 to 10 happy face scale, a child's maximum 10 actually being a 5 for an adult if you were to compare the injury, but normalising that to 5 would be wrong because it suggests the child could tolerate more (when in fact they would probably pass out). This basically highlights a single measurable scale only applies to electrical activity, not to perception, which arguably is what you really want to compare.