I know that the equations for obtaining the RAW regression coefficient of the slope and Pearson's correlation (r) are different, but conceptually, how do those two differ when you only have two variables?

Please let me know and thank you for your help!!

  • $\begingroup$ What exactly do you mean by a "RAW" regression coefficient? $\endgroup$ – whuber Jan 26 '17 at 21:19
  • $\begingroup$ I think you will find the information you need in the linked thread. Please read it. If it isn't what you want / you still have a question afterwards, come back here & edit your question to state what you learned & what you still need to know. Then we can provide the information you need without just duplicating material elsewhere that already didn't help you. $\endgroup$ – gung - Reinstate Monica Jan 26 '17 at 22:02

In case of simple regression where we use $X$ to predict $Y$, the relation is as follows

$$ \hat {\beta} = \frac{\rm{cov}(X, Y) }{ \rm{var}(X)} = {\rm cor}(Y, X) \cdot \frac{ {\rm SD}(Y) }{ {\rm SD}(X) } $$

while correlation is

$$ {\rm cor}(X, Y) = \frac{ {\rm cov}(Y, X) }{ {\rm SD}(Y) \,{\rm SD}(X) } $$

So in the case of just two variables, regression slope is re-scaled (not in $[-1,1]$) and non-symmetric (slope for $Y$ given $X$ is different then for $X$ given $Y$) correlation coefficient.

  • $\begingroup$ Wow, you managed to post an answer 38 minutes after the question was closed. $\endgroup$ – amoeba Jan 26 '17 at 23:21
  • $\begingroup$ @amoeba yes that's strange... I started writing it, then was doing other things and came back to post it half an hour later. $\endgroup$ – Tim Jan 27 '17 at 5:59

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