In: Statistics and Probability
A statistical program is recommended.
The owner of a movie theater company would like to predict weekly gross revenue as a function of advertising expenditures. Historical data for a sample of eight weeks follow.
Weekly Gross Revenue ($1,000s) |
Television Advertising ($1,000s) |
Newspaper Advertising ($1,000s) |
---|---|---|
96 | 5 | 1.5 |
91 | 2 | 2 |
95 | 4 | 1.5 |
93 | 2.5 | 2.5 |
95 | 3 | 3.2 |
94 | 3.5 | 2.3 |
94 | 2.5 | 4.2 |
94 | 3 | 2.5 |
(a)
Use α = 0.01 to test the hypotheses
H0: | β1 = β2 = 0 |
Ha: | β1 and/or β2 is not equal to zero |
for the model
y = β0 + β1x1 + β2x2 + ε,
where
x1 | = | television advertising ($1,000s) |
x2 | = | newspaper advertising ($1,000s). |
Find the value of the test statistic. (Round your answer to two decimal places.)
Find the p-value. (Round your answer to three decimal places.)
p-value =
State your conclusion.
Reject H0. There is sufficient evidence to conclude that there is a significant relationship among the variables.Do not reject H0. There is insufficient evidence to conclude that there is a significant relationship among the variables. Reject H0. There is insufficient evidence to conclude that there is a significant relationship among the variables. Do not reject H0. There is sufficient evidence to conclude that there is a significant relationship among the variables.
(b)
Use α = 0.05 to test the significance of
β1.
State the null and alternative hypotheses.
H0: β1 = 0 |
Ha: β1 > 0 |
H0: β1 < 0 |
Ha: β1 = 0 |
H0: β1 = 0 |
Ha: β1 ≠ 0 |
H0: β1 = 0 |
Ha: β1 < 0 |
H0: β1 ≠ 0 |
Ha: β1 = 0 |
Find the value of the test statistic. (Round your answer to two decimal places.)
Find the p-value. (Round your answer to three decimal places.)
p-value =
State your conclusion.
Reject H0. There is insufficient evidence to conclude that β1 is significant.Do not reject H0. There is insufficient evidence to conclude that β1 is significant. Reject H0. There is sufficient evidence to conclude that β1 is significant.Do not reject H0. There is sufficient evidence to conclude that β1 is significant.
Should
x1
be dropped from the model?
YesNo
(c)
Use α = 0.05 to test the significance of
β2.
State the null and alternative hypotheses.
H0: β2 = 0 |
Ha: β2 ≠ 0 |
H0: β2 < 0 |
Ha: β2 = 0 |
H0: β2 = 0 |
Ha: β2 > 0 |
H0: β2 = 0 |
Ha: β2 < 0 |
H0: β2 ≠ 0 |
Ha: β2 = 0 |
Find the value of the test statistic. (Round your answer to two decimal places.)
Find the p-value. (Round your answer to three decimal places.)
p-value =
State your conclusion.
Reject H0. There is sufficient evidence to conclude that β2 is significant.Reject H0. There is insufficient evidence to conclude that β2 is significant. Do not reject H0. There is sufficient evidence to conclude that β2 is significant.Do not reject H0. There is insufficient evidence to conclude that β2 is significant.
Should
x2
be dropped from the model?
YesNo
Perform multiple regression In Rstudio:
Use lm function in R to fit Y on x1 and x2
coeffcients function to get the coeffcients
Summary function to get t,p values
Rcode:
df1 =read.table(header = TRUE, text ="
y x1 x2
96 5 1.5
91 2 2
95 4 1.5
93 2.5 2.5
95 3 3.2
94 3.5 2.3
94 2.5 4.2
94 3 2.5
"
)
df1
linreg=lm(y~x1+x2 ,data=df1)
coefficients(linreg)
summary(linreg)
Output:
> df1
y x1 x2
1 96 5.0 1.5
2 91 2.0 2.0
3 95 4.0 1.5
4 93 2.5 2.5
5 95 3.0 3.2
6 94 3.5 2.3
7 94 2.5 4.2
8 94 3.0 2.5
> linreg=lm(y~x1+x2 ,data=df1)
> coefficients(linreg)
(Intercept) x1 x2
85.9101271 1.8090433 0.9435725
> summary(linreg)
Call:
lm(formula = y ~ x1 + x2, data = df1)
Residuals:
1 2 3 4 5 6 7
-0.3707 -0.4154 0.4383 0.2083 0.6433 -0.4120 -0.3957
8
0.3038
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 85.9101 1.2970 66.237 1.49e-08 ***
x1 1.8090 0.2493 7.256 0.000777 ***
x2 0.9436 0.2666 3.540 0.016569 *
---
Signif. codes:
0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Residual standard error: 0.525 on 5 degrees of freedom
Multiple R-squared: 0.9139, Adjusted R-squared:
0.8794
F-statistic: 26.53 on 2 and 5 DF, p-value: 0.002177
ANSWER(A)
Find the value of the test statistic. (Round your answer to two decimal places.)
F=26.53
Find the p-value. (Round your answer to three decimal places.)
p-value =0.002
p<0.01
State your conclusion.
Reject H0. There is sufficient evidence to conclude that there is a significant relationship among the variables
ANSWER(B)
H0: β1 = 0 |
Ha: β1 ≠ 0 |
Find the value of the test statistic. (Round your answer to two decimal places.)
t= 7.26
Find the p-value. (Round your answer to three decimal places.)
p=0.001
p<0.05
Reject Ho
Reject H0. There is sufficient evidence to conclude that β1 is significant
NO it should not be dropped form model.
ANSWER(C)
H0: β2 = 0 |
Ha: β2 ≠ 0 |
Find the value of the test statistic. (Round your answer to two decimal places.)
t=3.54
p-value = 0.017
p<0.05
.Reject H0. There is insufficient evidence to conclude that β2 is significant.
NO it should not be dropped form model