In: Statistics and Probability
Consider the following data on price ($) and the overall score for six stereo headphones tested by a certain magazine. The overall score is based on sound quality and effectiveness of ambient noise reduction. Scores range from 0 (lowest) to 100 (highest).
Brand | Price ($) | Score |
---|---|---|
A | 180 | 74 |
B | 150 | 73 |
C | 95 | 63 |
D | 70 | 58 |
E | 70 | 40 |
F | 35 | 28 |
Find the value of the test statistic. (Round your answer to three decimal places.)_____
Find the p-value. (Round your answer to four decimal places.)
p-value = ____
2.-Test for a significant relationship using the F test. Use α = 0.05.
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 = ____
What is your conclusion?
Reject H0. We conclude that the relationship between price ($) and overall score is significant.
Do not reject H0. We conclude that the relationship between price ($) and overall score is significant.
Reject H0. We cannot conclude that the relationship between price ($) and overall score is significant.
Do not reject H0. We cannot conclude that the relationship between price ($) and overall score is significant.
(c)Show the ANOVA table for these data. (Round your p-value to three decimal places and all other values to two decimal places.)
Source of Variation |
Sum of Squares |
Degrees of Freedom |
Mean Square |
F | p-value |
---|---|---|---|---|---|
Regression | |||||
Error | |||||
Total |
In order to solve this question I used R software.
R codes and output:
> price=c(180,150,95,70,70,35)
> score=c(74,73,63,58,40,28)
> fit=lm(price~score)
> summary(fit)
Call:
lm(formula = price ~ score)
Residuals:
1 2 3 4 5 6
32.573 5.208 -23.444 -35.270 12.157 8.775
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) -47.5498 39.4593 -1.205 0.2946
score 2.6348 0.6747 3.905 0.0175 *
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Residual standard error: 27.87 on 4 degrees of freedom
Multiple R-squared: 0.7922, Adjusted R-squared: 0.7403
F-statistic: 15.25 on 1 and 4 DF, p-value: 0.01747
> anova(lm(price~score))
Analysis of Variance Table
Response: price
Df Sum Sq Mean Sq F value Pr(>F)
score 1 11843.5 11843.5 15.25 0.01747 *
Residuals 4 3106.5 776.6
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
>
Que.1
Test statistic for testing slope coefficient is t = 3.905
and p value = 0.0175
Since p-value is less than 0.05, slope coefficient is statistically significant.
Que.2
F test = 15.25
p-value= 0.0175
Since p-value is less than 0.05, we reject H0 and
conclude that relationship between price and overall score is
significant.
c. ANOVA table:
Source of variation | SS | DF | MS | F | p-value |
Regression | 11843.5 | 1 | 11843.5 | 15.25 | 0.0175 |
Error | 3106.5 | 4 | 776.625 | ||
Total | 14950 | 5 |