Shown below is output from two Excel regression analyses on the same problem. The first output was done on a “full” model. In the second output, the variable with the smallest absolute t value has been removed, and the regression has been rerun like a second step of a backward elimination process. Examine the two outputs. Explain what happened, what the results mean, and what might happen in a third step.
FULL MODEL
Regression Statistics
Multiple R
0.567
R Square
0.321
Adjusted R Square
0.208
Standard Error
159.681
Observations
29
ANOVA
Significance
df
SS
MS
F
Regression
4
289856.08
72464.02
2.84
0.046
Residual
24
611955.23
25498.13
Total
28
901811.31
Coefficients
t Stat
P-value
Intercept
336.79
124.0800
2.71
0.012
X1
1.65
1.7800
0.93
0.363
X2
−5.63
13.4700
−0.42
0.680
X3
0.26
1.6800
0.16
0.878
X4
185.50
66.2200
2.80
0.010
SECOND MODEL
0.566
0.239
156.534
3
289238.1
96412.70
3.93
0.020
25
612573.20
24502.90
901811.3
342.92
11.34
2.97
0.006
1.83
1.31
1.40
0.174
−5.75
13.18
−0.44
0.667
181.22
59.05
3.07
0.005
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