… that this blog post is NOT going to do the topic justice. but i will trudge on nonetheless.
just because two things are moving together doesn’t mean they are causing each other
you can’t conclude that something causes something unless you have (1) thoroughly reviewed previously written research, (2) looked at alternative reasons why the two may be – and may not be causal, and (3) checked with common-sense. a high “r-coefficient” or a high “r-squared” doesn’t mean anything.
if you don’t have an explanation why would A cause B – and why not something else (say, another variable C), and why not the other way around – i.e., B causes A – chances are the “causal relationship” is spurious.
once again, there’d be remarks that this is too academic.
but it isn’t.
it’s simple, common-sense.