Note: You must change the data table by X2 = 0 (for mechanical) and X2 =1 (for e

Question

Note: You must change the data table by X2 = 0 (for mechanical) and X2 =1 (for electrical), and also X3 = 0 (for Bob Jones) and X3 =1 (for Dave Newton) BEFORE running regression! Use alpha = 0.05

a. Develop the Regression equation

b. How much of the variation in Satisfaction is explained by the variation in the independent variables ( Adjusted Coefficient of Determination)?

Repair Time in Hours (Y) Months Since Last Service (X2) Type of Repair (X2) Repairperson (X3) 2.9 2 Electrical Dave Newton 3 6 Mechanical Dave Newton 4.8 8 Electrical Bob Jones 1.8 3 Mechanical Dave Newton 2.9 2 Electrical Dave Newton 4.9 7 Electrical Bob Jones 4.2 9 Mechanical Bob Jones 4.8 8 Mechanical Bob Jones 4.4 4 Electrical Bob Jones 4.5 6 Electrical Dave Newton

Explanation / Answer

I have done this using minitab. steps are listed here

1) Enter the data in worksheet

2) Go to Stat

3) Select Regression

4) Select Fit regression model

5) put Y in "responses"

6) X1=Months Since Last Service in "continuous predictors"

7)X2=Type of Repair and X3= Repairperson in categorical covariates

click ok.

The adjusted R-squared is 85.03% this is the amount of variation explained.

Since we have 2 categorical variables X2 and X3 we wil have 4 regression equations (for the pairs (X2,X3)= (1,1),(0,0),(1,0),(0,1)

Regression Equation

X2 X3
0   0   Y = 1.860 + 0.2914 X1

0   1   Y = 1.251 + 0.2914 X1

1   0   Y = 2.963 + 0.2914 X1

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