I am searching for the formula to calculate the correlation coefficient in case of multiple linear regression.
I have 2 independent variables $X1$ and $X2$, and 1 dependent variable $Y$. I want to study whether there is correlation between the 3 parameters.
The model is
$$ Y = aX1 + bX2 + c $$
I was able to calculate $a$, $b$, and $c$. Now I need to 'analyze' whether there is a correlation. In case of linear regression $x$ and $y$, the formula is:
$$ r = \frac{cov(x,y)}{ \sqrt{var(x)var(y)} } $$
What is the formula in case of $x1$, $x2$, and $y$.
Is it called multiple correlation?
multiple correlation
the term word I am looking for? $\endgroup$