Question 1

Two variables that are actually not related to each other may nonetheless have a very high correlation because they both result from some other, possibly hidden, factor.This is an
Example of

Accepted Answer

A)  leverage.
B)  regression.
C)  an outlier.
D)  a lurking variable.
E)  extrapolation. C

Question 2

A residual plot that has no pattern is a sign that…

Accepted Answer

A)  the original data is straight and the regression line is a good model.
B)  the original data is straight and the regression line is not a good model.
C)  the model is not a good one, because there is no pattern.
D)  the original data is curved and the regression line is not a good model.
E)  the original data is curved and the regression line is a good model. D

Question 3

Linear regression was used to describe the trend in world population over time.Below is a plot of the residuals versus predicted values.What does the plot of residuals suggest?

Accepted Answer

A)  An outlier is present in the data set.
B)  The linearity condition is not satisfied.
C)  A high leverage point is present in the data set.
D)  The data are not normal.
E)  The equal spread condition is not satisfied. B

Question 4

When using midterm exam scores to predict a student's final grade in a class, the student would prefer to have a

Accepted Answer

A)  negative residual, because that means the student's final grade is lower than we would predict with the model.
B)  residual equal to zero, because that means the student's final grade is exactly what we would predict with the model.
C)  positive residual, because that means the student's final grade is lower than we would predict with the model.
D)  positive residual, because that means the student's final grade is higher than we would predict with the model.
E)  negative residual, because that means the students final grade is higher than we would predict with the model.

Question 5

Another farmer has increased his wheat production by about the same percentage each year. His most useful predictive model is probably…

Accepted Answer

A)  linear
B)  exponential
C)  logarithmic
D)  quadratic
E)  power

Question 6

Over the past decade a farmer has been able to increase his wheat production by about the same number of bushels each year.His most useful predictive model is probably…

Accepted Answer

A)  linear
B)  logarithmic
C)  quadratic
D)  exponential
E)  power

Question 7

Which of the following is not a goal of re-expressing data?

Accepted Answer

A)  Make the scatter in a scatterplot spread out evenly rather than following a fan shape.
B)  Make the spread of several groups more alike.
C)  All of these are goals of re-expressing data.
D)  Make the form of a scatterplot more nearly linear.
E)  Make the distribution of a variable more symmetric.

Question 8

Which statement about residuals plots is true? I.A curved pattern indicates nonlinear association between the variables.
II)A pattern of increasing spread indicates the predicted values become less reliable as the
Explanatory variable increases.
III)Randomness in the residuals indicates the model will predict accurately.

Accepted Answer

A)  I only
B)  II only
C)  I, II, and III
D)  I and III only
E)  I and II only

Question 9

Which of the following is not a source of caution in regression between two variables?

Accepted Answer

A)  subgroups with differences
B)  extrapolation
C)  a lurking variable
D)  an outlier
E)  all of these are potential problems.

Question 10

The $\sqrt { \text { str } } = 12 + 20 ($ dia $)$ can be used to predict the breaking strength of a rope (in pounds) from its diameter (in inches). According to this model, how much force should a rope onehalf inch in diameter be able to withstand?

Accepted Answer

A)    16lbs16 \mathrm { lbs }16lbs 
B)    22lbs22 \mathrm { lbs }22lbs 
C)    4.7lbs4.7 \mathrm { lbs }4.7lbs 
D)    256lbs256 \mathrm { lbs }256lbs 
E)    484lbs484 \mathrm { lbs }484lbs

Question 11

Which statement about re-expressing data is not true? I.Unimodal distributions that are skewed to the left will be made more symmetric by taking
The square root of the variable.
II)A curve in which the direction of the association changes from negative to positive will
Not benefit from re-expression.
III)One goal of re-expression may be to make the variability of the response variable more
Uniform.

Accepted Answer

A)  I only
B)  III only
C)  II only
D)  II and III
E)  I, II, and III

Question 12

A scatterplot of log(Y) vs.log(X) reveals a linear pattern with very little scatter.It is probably true that …

Accepted Answer

A)  the calculator's LnReg function will model the association between X and Y.
B)  the residuals plot for regression of Y on X shows a curved pattern.
C)  the correlation between X and Y is near 0.
D)  the correlation between X and Y is near +1.
E)  the scatterplot of Y vs X shows a linear association.

Question 13

If a data point is influential it…

Accepted Answer

A)  has a small residual.
B)  is guaranteed to be extreme in the vertical direction.
C)  is guaranteed to be extreme in the horizontal direction.
D)  will change the slope of the regression equation.
E)  none of these.

Question 14

A residuals plot is useful because I.it will help us to see whether our model is appropriate.
II)it might show a pattern in the data that was hard to see in the original scatterplot.
III)it will clearly identify influential points.

Accepted Answer

A)  I and II only
B)  I, II, and III
C)  II only
D)  I only
E)  I and III only

Question 15

Which is true?
I. Random scatter in the residuals indicates a model with high predictive power.
II. If two variables are very strongly associated, then the correlation between them will be near $+ 1.0$ or $- 1.0$.
III. The higher the correlation between two variables the more likely the association is based in cause and effect.

Accepted Answer

A)   I, II, and III
B)   none
C)   I only
D)   I and II
E)   II only

Question 16

Which statement about correlation is true? I.Regression based on data that are summary statistics tends to result in a higher
Correlation.
II)If r = 0.95, the response variable increases as the explanatory variable increases.
III)An outlier always decreases the correlation.

Accepted Answer

A)  I only
B)  II only
C)  III only
D)  I, II, and III

Question 17

The model $\sqrt { \text { distance } } = 3.30 + 0.235$ (speed. can be used to predict the stopping distance (in feet. for a car traveling at a specific speed (in mph.) According to this model, about how much distance will a car going $65 \mathrm { mph }$ need to stop?

Accepted Answer

A)    729.0729.0729.0  feet
B)    345.0345.0345.0  feet
C)    27.027.027.0  feet
D)    4.34.34.3  feet
E)    18.618.618.6  feet

Exam 8: Regression Wisdom

Two variables that are actually not related to each other may nonetheless have a very high correlation because they both result from some other, possibly hidden, factor.This is an Example of

A residual plot that has no pattern is a sign that…

Linear regression was used to describe the trend in world population over time.Below is a plot of the residuals versus predicted values.What does the plot of residuals suggest?

When using midterm exam scores to predict a student's final grade in a class, the student would prefer to have a

Another farmer has increased his wheat production by about the same percentage each year. His most useful predictive model is probably…

Over the past decade a farmer has been able to increase his wheat production by about the same number of bushels each year.His most useful predictive model is probably…

Which of the following is not a goal of re-expressing data?

Which of the following is not a source of caution in regression between two variables?

The $\sqrt { \text { str } } = 12 + 20 ($ dia $)$ can be used to predict the breaking strength of a rope (in pounds) from its diameter (in inches) . According to this model, how much force should a rope onehalf inch in diameter be able to withstand?

A scatterplot of log(Y) vs.log(X) reveals a linear pattern with very little scatter.It is probably true that …

If a data point is influential it…

A residuals plot is useful because I.it will help us to see whether our model is appropriate. II) it might show a pattern in the data that was hard to see in the original scatterplot. III) it will clearly identify influential points.

Which statement about correlation is true? I.Regression based on data that are summary statistics tends to result in a higher Correlation. II) If r = 0.95, the response variable increases as the explanatory variable increases. III) An outlier always decreases the correlation.

The model $\sqrt { \text { distance } } = 3.30 + 0.235$ (speed. can be used to predict the stopping distance (in feet. for a car traveling at a specific speed (in mph.) According to this model, about how much distance will a car going $65 \mathrm { mph }$ need to stop?

Exam 8: Regression Wisdom

Two variables that are actually not related to each other may nonetheless have a very high correlation because they both result from some other, possibly hidden, factor.This is an Example of

A residual plot that has no pattern is a sign that…

Linear regression was used to describe the trend in world population over time.Below is a plot of the residuals versus predicted values.What does the plot of residuals suggest?

When using midterm exam scores to predict a student's final grade in a class, the student would prefer to have a

Another farmer has increased his wheat production by about the same percentage each year. His most useful predictive model is probably…

Over the past decade a farmer has been able to increase his wheat production by about the same number of bushels each year.His most useful predictive model is probably…

Which of the following is not a goal of re-expressing data?

Which of the following is not a source of caution in regression between two variables?

The str =12+20(\sqrt { \text { str } } = 12 + 20 ( str ​=12+20( dia ) ) ) can be used to predict the breaking strength of a rope (in pounds) from its diameter (in inches) . According to this model, how much force should a rope onehalf inch in diameter be able to withstand?

A scatterplot of log(Y) vs.log(X) reveals a linear pattern with very little scatter.It is probably true that …

If a data point is influential it…

A residuals plot is useful because I.it will help us to see whether our model is appropriate. II) it might show a pattern in the data that was hard to see in the original scatterplot. III) it will clearly identify influential points.

Which statement about correlation is true? I.Regression based on data that are summary statistics tends to result in a higher Correlation. II) If r = 0.95, the response variable increases as the explanatory variable increases. III) An outlier always decreases the correlation.

The $\sqrt { \text { str } } = 12 + 20 ($ dia $)$ can be used to predict the breaking strength of a rope (in pounds) from its diameter (in inches) . According to this model, how much force should a rope onehalf inch in diameter be able to withstand?