Week 5 EText Assignment
In the following regression,
X
= weekly pay,
Y
= income tax withheld, and
n
= 35 McDonald’s
employees. (a) Write the fitted regression equation. (b) State the degrees of freedom for a two
tailed test for zero slope, and use Appendix D to find the critical value at
α
= .05. (c) What is
your conclusion about the slope? (d) Interpret the 95 percent confidence limits for the slope. (e)
Verify that
F
=
t
2 for the slope. (f) In your own words, describe the fit of this regression.
R2 0.202
Std. Error 6.816
n 35
ANOVA table
Source
SS
df
MS
F
pvalue
Regression
387.6959
1
387.6959
8.35
.0068
Residual
1,533.0614
33
46.4564
Total
1,920.7573
34
Regression output
confidence interval
variables
coefficients
std. error
t (df
=
33)
pvalue
95% lower
95% upper
Intercept
30.7963
6.4078
4.806
.0000
17.7595
43.8331
Slope
0.0343
0.0119
2.889
.0068
0.0101
0.0584
A)
7963
.
30
0343
.
^
+
=
x
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 Spring '08
 unknown
 Statistics, Normal Distribution, Regression Analysis, Prediction interval, critical value

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