On: Activity inequality

[synctext]

Agreed, there are red flags. All their data comes from this smartphone app (717,527 users):

  Download Argus now! Join MILLIONS and download the 
  world’s ONLY free all-in-one health & fitness app that 
  uses JUST your phone (no costly devices needed) and 
  conquer your goals! We have a super-easy calorie 
  counter with barcode scanner and massive food database.

As a scientist I would have rejected this Nature paper based on highly biased data collection.

[jaclaz → synctext]

I wonder WHO (in the sense of only a subset of a given population) would download and install that "all-in-one" tool.

I would guess:

1) people somehow interested in their fitness

2) people having some dietary issues (more probably believing to be more fat than what they should be and looking for a shortcut to get slimmer)

Customer of type #1 will likely do lots of steps, while customer of type #2 is more likely to do much less.

It is very possible that in whole coutries there is a preponderance of type #1 and in other ones of type #2.