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Comment by Avamander | Hacker News Reader

The thing that actually is surprising is how many researchers don't even mention why they've excluded the possibility of a reverse correlation in their studies.

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I think you meant to write "reverse causation"? Correlation is by definition symmetric and directionless. If the researchers make no causation claims, they don't need to be concerned about the direction of causation.

I haven't followed the field, but it's hard for me to imagine published research in serious academic journals where causation claims are made without at least some discussion about the direction of causation and hidden confounders.

It is likely that the poster was referring to a negative correlation. While incorrect terminology was used, correlations do have direction.

https://stats.stackexchange.com/questions/173276/is-it-corre...

https://study.com/academy/lesson/negative-correlation-in-psy...

Negative correlation also known as anticorrelation does not mean there is a "direction". Simply, it is a scalar number and not a vector. Don't add to the confusion of terminology by using a colloquial definition of "direction" to mean it can be negative or positive. We could have defined correlation to be in [0,1] and your sense of direction would be very confusing.

Thank you for the clarification, you are absolutely correct that its positive or negative rather than having a direction.

Probably, not my first language.

> If the researchers make no causation claims

But sentences like "kids using their phones more than x hours a day are on average sadder" very much imply one.

Like the worse your mental health is the more you are on your phone?

Or the more you enjoy the idea of shooting people in the face, the more time you're likely to spend playing video games involving shooting people in the face?

Yep, things like that. I would at least appreciate adding a disclaimer, that this behaviour might be a symptom of some other issues for example at school.

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