One complication with the Fitbit might be that if I were a study subject, then I could see my own data as it happens, and could potentially alter my behaviour to help it show what I thought the study wanted....
Of course just knowing it was being measured could mean a subject could still alter their behaviour, but they would have less knowledge of what they were actually clocking up.
I know I keep an eye on my Fitbit during the day a bit, and if I think I've been a bit busy I look and see if I really have and will moderate what I do based on that knowledge. Of course that is how I am using it... and it helps. I really do have fewer proper crashes now...
Of course just knowing it was being measured could mean a subject could still alter their behaviour, but they would have less knowledge of what they were actually clocking up.
I know I keep an eye on my Fitbit during the day a bit, and if I think I've been a bit busy I look and see if I really have and will moderate what I do based on that knowledge. Of course that is how I am using it... and it helps. I really do have fewer proper crashes now...