A multiple regression analysis showed the following results

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A multiple regression analysis showed the following results of the individual independent variables.

Coefficients

Standard Error

t-stat

p-value

Intercept

139.577

84.235

1.657

0.104

X1

-0.135

5.698

-0.024

0.981

X2

3.734

1.220

3.062

0.004

X3

2.448

26.524

-0.376

0.709

X4

-9.976

2.345

2.345

0.024

In stepwise regression, which independent variable would most likely be added first?

How are residual plots drawn and used to evaluate the assumptions of linear multiple regression?

Solution

X1 has the ighest p value. Hence it is the variable which is most likely to be added first.

Residual plot is drawn by taken the explanatory varibale along the x axis and residuals along the y axis. the residual plot should be like a scatter plot which will verify that the residuals do not follow any pattern. there must be equal number of residuals on both sides of the x axis. this verifies that the residuals have constant variance. We can also identify possible outliers by looking at the residual plot.