Question

Businesses who put an advertisement in the local newspaper would be interested in knowing the return against investment. A newspaper considered responses against 60 advertisements which appeared on different days of the week (Monday – Friday) and in three different pages (News, Business, Sports). The newspaper wanted to see whether (i) there is any difference in responses against ads appearing on different days of the week and (ii) there is any difference in responses against ads appearing on different sections of the newspaper. The following information is available. What is the Mean Square of Residuals?

Answer 1

Answer:

4.05

Step-by-step explanation:

Total df = 60-1 = 59

Days of a week df = 4

section df = 2

Thus Residual df = 59-4-2 = 53

Sum sq_residual = 415.33-146.83-53.73 = 214.77

Mean sq_ residual = Sum sq_residual / Residual df

                               = 214.77 / 53 = 4.05

Answer 2

4.05

Explanation:

• Number of ads = 60

• $\implies Total\ \delta_f = 60-1 = 59$

• $Days \ of \ a \ week \ \delta_f = 4$

• $\therefore \ section \ \delta_f =2$

• $\therefore \ residual \ of \ \delta_f = 59 -4 -2 = 53$

• $\Sigma sq_r_e_s_i_d_u_a_l = 415.33-146.83-53.73 = 214.77$

• $\bar \mu (sq_ r_e_s_i_d_u_a_l) = \frac{\Sigma sq_r_e_s_i_d_u_a_l}{Residual \delta_f}= 214.77 / 53 = 4.05$