Question / (Two parts totaling 3 marks): Consider the following model. u{Sales | magazines, TV, radio} = Bo + B,magazines + B,TV + Byradio + BA(magazines x TV) + Bs (magazines x radio) + Bo(TV x radio) + B, (magazines x TV x radio) (a) (2 marks): What is the effect of magazines on sales? How would you redefine the model? No calculations are necessary. u{Sales | magazines + 1, TV, radio} - u{Sales | magazines, TV , radio} = Bi + BA(TV) + Bs(radio) + B, (TV xradio) (b) (1 mark): What would be the null hypotheses for testing for the effect of magazines? Ho : B, = BA = Bs = By =0