why is the mean of all $y_i$ equal to 0? why does the mean of all y_i$ equal to 0 what is the means for all $y_i$ what is the mean of all $y_i$ why is the mean of all y_i$ equal to 0? which of the following is an equation for a linear regression? why is mean of all $y_i equal to 0? what is mean for all y_i$ what is the definition of epsilon_i$ in linear regression why does the mean of y_i equal to 0 how does mean in a linear regression differ from mean epsilon_i$s what is the mean for all $y_i$ equal to in a linear regression why is $y_i 0 why is the mean of all y_i$ equal why is the mean equal to 0 why is the mean of all $y_i$ equal to 0 what is the mean of all $y_i$ in a linear regression what is the mean of all $y_i$? what is mean of all $y_i$ in linear regression what is mean of all y_i$