>The most mentally healthy respondents are those who did not get a phone until their late teens. The first graph also shows that the oldest people score the be

>The most mentally healthy respondents are those who did not get a phone until their late teens. The first graph also shows that the oldest people score the best on their mental health test in general. --- They note that their Mental Health Quotient figure has been decreasing over the years. They also note that in the age range of 18-24 the earlier that the people were given a smartphone the worse the MHQ figure is. But did they control for age here? Because 18-24 is a 7 year duration. Their first graph shows that in a 7 year timeframe their MHQ graph drops 25%. We could be seeing an effect that the older part of the range got their smartphones at a later age (because it's new technology) and the correlated MHQ drop by year creates the drop off by age of first smartphone. Was this accounted for because I couldn't find it on a quick read. --- You might also be measuring the effect of better mental health awareness. Ie kids who got smartphones earlier might be more aware of mental health issues and are more likely to notice and bring it up.