In: Statistics and Probability
QUESTION 3
The following table contains ACT scores and the GPA for eight college students. Grade point average is based on a four-point scale and has been rounded to one digit after the decimal.
Student |
GPA |
ACT |
1 |
2.8 |
21 |
2 |
3.4 |
24 |
3 |
3 |
26 |
4 |
3.5 |
27 |
5 |
3.6 |
29 |
6 |
3 |
25 |
7 |
2.7 |
25 |
8 |
3.7 |
30 |
You estimate the following relationship between GPA and ACT:
SUMMARY OUTPUT |
||||||
Regression Statistics |
||||||
Multiple R |
0.759884064 |
|||||
R Square |
0.577423791 |
|||||
Adjusted R Square |
0.506994423 |
|||||
Standard Error |
0.269173202 |
|||||
Observations |
8 |
|||||
ANOVA |
||||||
df |
SS |
MS |
F |
Significance F |
||
Regression |
1 |
0.594024725 |
0.594024725 |
8.198622346 |
0.0286766 |
|
Residual |
6 |
0.434725275 |
0.072454212 |
|||
Total |
7 |
1.02875 |
||||
Coefficients |
Standard Error |
t Stat |
P-value |
Lower 95% |
Upper 95% |
|
Intercept |
0.568131868 |
0.928421385 |
0.611933199 |
0.563036476 |
-1.703633417 |
2.839897154 |
ACT |
0.102197802 |
0.035692019 |
2.863323654 |
0.0286766 |
0.014862578 |
0.189533026 |
a). (5) Compute the value of the least squares residual for the first student in the sample. Show your calculation.
b). (5) Interpret the intercept.
c). (5) Interpret the slope.
d). (10) Using the critical value approach, test whether we have a positive significant relationship between ACT and GPA. Set up the null and alternative. Use a level of significance of 5%.