Yes, this is an interesting aspect: I could get better EEG but what’s important to me is the phenomenon I’ve chosen to observe because it promises insight into my question. This phenomenon is not “EEG data” but rather “arrhythmia events.” Of course I already know I have these arrhythmias in general, and I know their type, thanks to a different measurement device (the Kardia by AliveCor), plus consultation with my cardiologist. And I already know there is quite a bit of variation over days, weeks, and months. But now I want to watch it more closely, both to see if I get any ideas about things to try, and to evaluate how well my medication is working. I’ve made nearly 10,000 observations using active tracking, and this indeed has given me quite a few ideas and insights. However, I was curious about what a biomedical measure would tell me, for several reasons. First, I needed a biomedical measure for discussion with my cardiologist, who was looking to see if the severity crossed certain thresholds, which would trigger treatment options. But second, I wanted to know if my self-measurement was basically coherent with the biomedical measurements. Most importantly, are we measuring the same thing; that is, arrhythmia incidents? As you suggest, I could be measuring a subjective feeling of arrhythmia that wasn’t really associated with the specific heart rhythm problems named by the cardiologist. Or, more likely, my ability to detect them was so influenced by the measurement conditions that there was little correlation between my daily score and the Zio daily score, which would make me look for some refinements in my approach. Getting twelve days of measurement that are so closely correlated is reassuring.
OK, you say, but how reassuring? I think I can answer this but I’m going to think a bit more before I do.