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- 1. Multiple Choice
Which of the followings correctly described an explanatory variable?
It explains changes in the response variable.
The variable that is manipulated by the researcher.
Independent variable.
Dependent variable
- 2. Multiple Choice
A researcher believes that the origin of the beans used to make a cup of coffee affects hyperactivity of the drinker. She wants to compare coffee from three different regions: Africa, Asia, and Mexico.
Identify the correct explanatory and response variables.
The explanatory variable is the coffee bean. The response variable is the drinker's reaction.
The response variable is hyperactivity level. The explanatory variable is the origin of coffee bean.
The response variable is the origin of coffee bean. The explanatory variable is hyperactivity level.
- 3. Multiple Choice
A correlation shows what type of relationship between two variables ?
Association
Cause and effect
Error
Ambiguous
- 4. Multiple Choice
Describe the correlation in the graph shown.
Strong, Negative, Linear
Strong, Positive, Linear
Weak, Negative, Curved
Moderate, Positive, Linear
- 5. Multiple Choice
Describe the correlation in the graph shown.
Weak Negative
Weak Positive
Strong Negative
Strong Positive
- 6. Multiple Choice
What type of correlation does this graph show?
Positive
Negative
Neither
All of the above
- 7. Multiple Choice
Outliers can affects correlation.
True
False
- 8. Multiple Choice
A data set included the number of people per television set and the number of people per physician for 40 countries. The scatterplot below shows the least-squares regression line. In Ethiopia, there are 503 people per TV and 36,660 people per doctor. What effect would removing this outlier have on the regression line?
Slope would increase; y intercept would increase
Slope would decrease; y intercept would increase
Slope would increase; y intercept would decrease
Slope and y intercept would stay the same
- 9. Multiple Choice
Which of the following correlation coefficients indicates the strongest relationship between variables?
0.5
-0.5
-0.9
0.7
0.3
- 10. Multiple Choice
In a medical school, it is found that there is a correlation of −0.98 between the amount of coffee consumed by students and the number of hours students sleep each night. Which of the following statement is true?
A. There is a positive association between the two variables.
B. There is a strong correlation between the two variables.
C. Coffee consumption in medical school students causes students to sleep less each night.
A & B
A & C
B only
None of the above
- 11. Multiple Choice
Interpret the slope of the Least Squares Line Equation.
Income increases by 31.45 with each additional 2 hours worked.
The base income is 242.3
As hours increases by one, income is predicted to increase by 31.45 on average.
As hours increases by one, income will decrease by 242.3.
- 12. Multiple Choice
In regression, the residuals are which of the following?
Those factors unexplained by the data
Those data which were recorded after investigation was completed
Outliers
The difference between the observed responses and the values predicted by the regression line
- 13. Multiple Choice
In a statistics course, a linear regression equation was computed to predict the final exam score from the score on the first test. The equation was y = 10 + .9x where y is the final exam score and x is the score on the first test. Carla scored 95 on the first test. On the final exam, Carla scored 98. What is the value of her residual?
3
2.5
-2.5
0
None of the above
- 14. Multiple Choice
X = diameter of tree trunk in inches, and Y = tree height in feet. If the LSRL equation is y = –3.6 + 3.1x, what is your estimate of the average height of all trees having a trunk diameter of 7 inches?
20.1
19.3
18.1
17.3
- 15. Multiple Choice
For children between the ages of 18 months and 29 months, there is an approximately linear relationship between height and age. The relationship can be represented by y^=64.93+0.63x, where y^ presents height (in centimeters) and x represents age (in months).
Linda is 20 months old and is 80 centimeters tall. What is her residual?
2.47
-2.47
12.60
-12.60
- 16. Multiple Choice
You are interested in predicting the cost of heating houses on the basis of how many rooms the house has. A scatterplot of 25 houses reveals a strong linear relationship between these variables, so you calculate a least-squares regression line. “Least-squares” refers to
Minimizing the sum of the squares of the number of rooms in each of the 25 houses.
Minimizing the sum of the products of each house’s actual heating costs and the predicted heating cost based on the regression
equation.
Minimizing the sum of the squares of the residuals.
Minimizing the sum of the squares of the difference between each house’s heating costs and number of rooms.
- 17. Multiple Choice
A study of the fuel economy for various automobiles plotted the fuel consumption vs. speed. A least squares line was fit to the data. Above is the residual plot from this least-squares fit. What does the pattern of the residuals tell you about the linear model?
The residual plot confirms the linearity of the data.
The residual plot clearly contradicts the linearity of the data.
The residual plot does not confirm nor rule out the linearity of the data.
A residual plot is not an appropriate means for evaluating a linear model.
- 18. Multiple Choice
A researcher wants to know if it's possible to predict arm span from height. The following computer regression printout shows the results of a least-squares regression of arm span on height, both in inches, for a sample of 18 high school students. The students’ arm spans ranged from 62 to 76 inches.
Which of the following statements is true?
The correlation between height and arm span is .871.
For every one-inch increase in arm span, the regression model predicts about a 0.84-inch increase in height.
For a student 66 inches tall, this model would predict an arm span of about 68 inches.
If one of the students in the sample had a height of 70 inches and an arm span of 68 inches, then the residual for this student would be about –2.36 inches.
- 19. Multiple ChoiceThe point in the upper right hand corner of the scatterplot isnot an outlier or an influential pointnot an outlier but an influential pointan outlier and an influential pointan outlier but not an influential point
- 20. Multiple ChoiceA study showed that students who spend more time studying for statistics tests tend to achieve better scores on their tests. In fact, the number of hours studied turned out to explain 81% of the observed variation in test scores among the students who participated in the study. What is the value of the correlation between number of hours studied and test score?r = 0.81r = 0.656r = 0.9There is no way to know.
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