My personal observation is that "screen time" is not the problem, but lack of interaction _is_ - letting the kids be in front of a screen for two hours doesn't cause a problem, but letting that be an excuse not to spend time with them or interact with them (which is when it usually ends up happening in large quantities) does. Essentially - you need to control the other variables to understand what's really going on; excessive screen time is generally a symptom and not a cause.