Multiple Regression Analysis Detailed Example: Delivery Time Multiple Regression

Analysis Step 1

At the first step, the following model is fitted the data to explain the relationship between the delivery time (y) and the number of cases delivered (x1) and the distance between the center and the delivered place (x2).

(See the APPENDIX 1 for the MINITAB output)

The fitted regression equation is obtained as follows:

Delivery Time (y)= 2,34 + 1,62 Number of Cases (x1) + 0,0144 Distance, x2 (ft).

To be sure that the validity of the model fitted, we check the LINE assumptions. For this purpose, the following residual analysis is conducted:

Check for LINE assumptions related to the above fitted model:

1. Normality of errors:

When we look at the Normal Probability Plot (NPP) of (standardized) residuals, it can be seen that standardized residuals do not follow the reference line closely; also there seems to be an outlier observation, whose standardized residual is greater than 3.