Exposure

[wjchulme]

This is "computer use during weekday and weekends at 16 years old".

There are two self-reported variables, comp_week and comp_wend, defined as the "average time child spent per day using a computer of a typical week/weekend day".
Presumably we should correct for the fact that there are 5 weekdays and 2 weekend days, so comp_all = (comp_week/5 + comp_wend/2)*7. Or should we consider these variables separately? Something more sophisticated?

[jspickering]

I just realised I thumbsed up without expanding!

I, personally, would think that the variables would be separate. I'm not sure what I'm basing this on, other than a gut feeling, but I would think that a high weekend computer usage may be associated with depression moreso than weekday.

Causally, it could be that existing depression leads to more computer use (staying inside, not socialising etc). It could be (though I doubt this for reasons I also can't explain as any more than a gut feeling) that computer use leads to depression. I think the key question by the main MAPS team used the word "associated", rather than implying any sort of causality?

Either way, a teenager on a computer on weekday evenings is probably pretty common. Homework, social media etc. A teenager on a computer for many hours (though what is "many"?) at the weekend might be more worrying.

[lanabojanic]

I'd keep them separate as well. Would personally argue that weekend computer use can be a stronger predictor for depression