Predicts vs Correlated With

If I see a correlation between two variables, is it generally correct terminology to say that one “predicts” the other? For example, in this chart, should I say that hours studied predict the grade received?

I would think one shouldn’t say “predicts” because that is a one-way term. For example, it is possible that A predicts B but B does not predict A. Waking up 10 minutes before sunrise every day predicts getting to see the sunrise often, but seeing the sunrise often wouldn’t necessarily predict your wake up time, especially if you work the night-shift.

I would say “there is a correlation between A and B” but without more research on the directionality of the relationship, I shouldn’t say “A predicts B” or “B predicts A”.

I’m asking because I’ve seen a few research papers that use this terminology and I wonder if I should adopt it.


  1. Carol says:

    I would avoid “predicts” because it implies causation. In your example, at least waking up 10 minutes before sunrise has some connection with seeing the sun rise (although you might miss the sunrise even if you woke up early enough, for example if you kept the curtains drawn). However, some things can be correlated with no causation either way. See this link for some hilarious examples. Even if, for example, “US spending on science, space, and technology” has historically been correlated with “Suicides by hanging, strangulation and suffocation,” I would think it a stretch to say that the former predicted the latter.

    Oh, and on an unrelated matter, why do you have a “link” button on your comment form when including a link will get the comment blocked?

  2. lee says:

    That’s what I’ve been thinking. The research I was looking at in a peer reviewed journal (that shall remain nameless) let it slip into this article in multiple places which is why I was asking. :-(

    About the “link” button: blocking “http://” is currently the ONLY spam blocking I have on the site and it stops 3,500 spams/week, letting only about 1/week through. (wow!) I suppose I should change that button. What I normally do when posting comments is use the button and then change it to “ttp://”… then I edit the comment to make a usable link. Sorry it’s not easier for everyone but this is how my spam strategy has evolved.

    PS, I -love- that correlation humor site! Thanks!

  3. lee says:

    PPS. I see that you figured out how to edit your comment and add the link using exactly the method I suggested. Sorry it has to be so serpentine.

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