The study also refers to heavy use but does not define what heavy means.
Heavy media use in a household is defined as one in which the television is on all or most of the time.What if everyone including the child is regularly out of the house for all but a few waking hours per day?
"the television" -- which one? Does the one in the teenager's bedroom count? How do computers factor in?
Please tell me they used stricter and more thorough criteria than that for "heavy media use".