The observer’s paradox is a problem in psychology basically stating that merely observing a problem affects the outcome. I’ve talked about this regarding my resting heartrate; when I’m thinking about it (and during a blood pressure test, you’re thinking about it), I consciously reduce the number.
How? Years of; meditation, breathing exercises, and using breathing and bio-feedback to reduce my heartrate.
Why? Basically, I don’t like the feeling of my heart beating hard. It feels…wrong, somehow. Unless I’m exercising hard.
So, if the observer’s paradox is messing up your tests, what do you do? Increase the data collection time frame to the point that your awareness moves away and you get untainted readings.
How? Now it’s easier than ever. Smartwatches (Fitbit, Apple watch, Garmin, etc.) take this data 24/7, and you can’t maintain focus over that period of time.
Yes, the data aren’t as good as those given by purpose-designed medical diagnostic equipment, but the time periods are so much longer that, along with removing the paradox, other sources of signal noise are also removed from the data.