I think the benefit is that the iPhone has sensors that can collect lots of data. For example, the Perkinson's(?) app makes you tap on two targets quickly and s

I think the benefit is that the iPhone has sensors that can collect lots of data. For example, the Perkinson's(?) app makes you tap on two targets quickly and say "aaaaa" for long and analyzes the ups and downs in vocal cords using the mic. Patients can't track all this by themselves. Plus, it will automatically send it to researchers. Much easier than making someone enter information on surveymonkey or polldaddy.