AP Statistics · Topic 9.5
Carrying Out a Test for the Slope of a Regression Model Practice
Part of Inference for Quantitative Data: Slopes.(VAR-7.F)
Practice questions
17
Sample questions
5 of 17 — sign in to practice the rest with adaptive difficulty and mastery tracking.
Sample 1difficulty 1/5
A simple linear regression is fit on n = 30 observations.
What is df for the t-test on slope?
- A
27
- B
29
- C
30
- Dcheck_circle
28
Why
df = n - 2 = 30 - 2 = 28 (estimating intercept and slope).
- A
Sample 2difficulty 2/5
A regression output reports residual df = 17.
What is the sample size n?
- A
18
- B
20
- Ccheck_circle
19
- D
17
Why
df = n - 2, so n = df + 2 = 17 + 2 = 19.
- A
Sample 3difficulty 2/5
A regression of weekly sales (y, in thousands) on advertising spend (x) gives the output below.
What is the estimated slope?
- A
4.80
- B
12.5
- Ccheck_circle
2.4
- D
0.5
Why
The slope is the coefficient on x: 2.4. The constant 12.5 is the intercept.
- A
Sample 4difficulty 2/5
The same regression output is shown with slope estimate 2.4 and SE = 0.5.
What is the t-statistic for testing H0: beta = 0?
- Acheck_circle
4.80
- B
12.50
- C
2.40
- D
0.50
Why
t = (b - 0)/SE(b) = 2.4/0.5 = 4.80, as shown.
- A
Sample 5difficulty 2/5
Computer output shows slope = 4.2 with SE = 1.4, n = 30.
What is the t-statistic?
- Acheck_circle
3.0
- B
5.6
- C
1.4
- D
2.5
Why
t = b / SE(b) = 4.2 / 1.4 = 3.0.
- A