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Dec 15, 2019 at 14:50 comment added whuber This answer is good, but the final formula is incorrect because $\sqrt{R^2}=|R| \ge 0$ whereas the correlation can be negative.
Jul 28, 2017 at 1:45 comment added Yannis Vassiliadis So how is what I wrote not correct? The sign of the correlation and the sign of the coefficient match.
Jul 28, 2017 at 1:42 comment added Michael R. Chernick This is not correct. The correlation is proportional to the slope and if the slope is negative so is the corrrealtion.
Jul 27, 2017 at 23:19 comment added Yannis Vassiliadis It is not independent. Say you regress $y$ on $x_1$ and $x_2$, and you get significant coefficients $\hat{\beta_1}$ and $\hat{\beta_2}$. Now repeat by omitting $x_2$. Now you have $\hat{\beta_1'}$, which is equal to $\hat{\beta_1}$ plus some bias. The bias is proportional to the correlation between $x_1$ and $x_2$, so the coefficient is not independent of the other variables (to be more precise, the variables are not independent of each other). In any case, none of these are applicable in a simple linear regression setting, was asked in the original question.
Jul 27, 2017 at 23:09 vote accept user2728024
Jul 27, 2017 at 23:06 comment added user2728024 But the coefficient for a variable should be independent of the other variables, since its the change in outcome with a unit increase in the value of that particular variable. Please correct me if I am wrong.
Jul 27, 2017 at 23:03 history edited Yannis Vassiliadis CC BY-SA 3.0
added 45 characters in body
Jul 27, 2017 at 23:03 vote accept user2728024
Jul 27, 2017 at 23:09
Jul 27, 2017 at 23:02 comment added Yannis Vassiliadis When you said simple linear regression, I assumed you meant with only one independent variable. In that case, it should always match. If it's multiple independent variables, then no, it really doesn't have to match. A correlation is a measure of the linear relationship between 2 variables, while a multiple regression is a measure of the linear relationship between $y$ and multiple $x$s.
Jul 27, 2017 at 22:56 comment added user2728024 If it's not matching, then what could be the reason? Can collinearity couse the issue?
Jul 27, 2017 at 22:42 history answered Yannis Vassiliadis CC BY-SA 3.0