AP Statistics · Topic 2.7
Residuals Practice
Part of Exploring Two-Variable Data.(DAT-1.D)
Practice questions
9
Sample questions
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Sample 1difficulty 1/5
A regression model predicts y-hat = 8 for an observation whose actual y-value is 11.
What is the residual?
- Acheck_circle
3
- B
11
- C
-3
- D
8
Why
Residual = observed - predicted = 11 - 8 = 3.
- A
Sample 2difficulty 2/5
A regression predicts y-hat = 2x + 5. For x = 6, the observed y is 14.
What is the residual?
- A
-17
- Bcheck_circle
-3
- C
17
- D
3
Why
y-hat = 2(6) + 5 = 17. Residual = 14 - 17 = -3.
- A
Sample 3difficulty 2/5
For the line y-hat = 10 + 3x with observation (x=4, y=20).
What is the residual?
- A
20
- B
22
- Ccheck_circle
-2
- D
2
Why
Residual = observed - predicted = 20 - 22 = -2.
- A
Sample 4difficulty 2/5
Consider the residuals from a least-squares regression line.
Which statement is always true?
- A
All residuals are positive
- B
Residuals equal predicted values
- C
The sum of squared residuals equals 0
- Dcheck_circle
The sum of the residuals equals 0
Why
The least-squares method produces residuals that sum to 0 (when an intercept is included).
- A
Sample 5difficulty 3/5
Output for predicting weight from height shows residual SD s = 10.
Which interpretation of s is best?
- A
The line passes within 10 inches of every point
- Bcheck_circle
Typical prediction error is about 10 lb
- C
10 lb equals the slope of the line
- D
About 10% of observations are below the line
Why
s estimates the typical (root-mean-square) size of residuals, i.e., the typical prediction error.
- A