why does linear regression use a correlation coefficient how do you determine linear regression value why do we need the correlation coefficient why do we need a correlation coefficient why do we need a correlation coefficient in linear regression why do we need r 2$ in regression why is $r2$ needed which parameter is used to calculate the linear relationship between a prediction and an observed value? what is the value of the correlation coefficient why should we use r for linear regression how to use the correlation coefficient in linear regression what is the coefficient of a linear regression why do we need $r to determine linear regression why use r2 in linear regression why use correlation coefficient? what is the correlation coefficient and why do i need $r=2$ why do we use correlation coefficient why do i need a correlation coefficient why do we require a correlation coefficient why do we need r in regression?