In the regression equation ( Y = a + b1 X1 + b2 X2 + … + bkXk ), what does the term (a) represent?
1
The effect of the predictor variable (X1) on the dependent variable (Y).
2
The slope of the predictor variable (X2).
3
The intercept of the regression line when all predictor variables are zero.
4
The error term not explained by the model.