Question 1

Suppose the correlation, r, between two variables x and y is -0.44.What percentage of the
Variability in y cannot be explained by x?

Accepted Answer

A) 19% 
B) 44% 
C) 81% 
D) 88% 
E) 12% 
A) 19% 
B) 44% 
C) 81% 
D) 88% 
E) 12% A

Question 2

A regression analysis of students' college grade point averages (GPAs) and their high school GPAs found $R ^ { 2 } = 0.311$. Which of these is true?
I. High school GPA accounts for $31.1 \%$ of college GPA.
II. $31.1 \%$ of college GPAs can be correctly predicted with this model.
III. $31.1 \%$ of the variance in college GPA can be accounted for by the model

Accepted Answer

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

Question 3

A small independent organic food store offers a variety of specialty coffees.To determine Whether price has an impact on sales, the managers kept track of how many pounds of each Variety of coffee were sold last month.  
$$\begin{array} { | l | l | l | } 
\hline & \text { PRICE PER POUND } & \text { POUNDS SOLD } \
\hline & \$ 3.99 & 75 \
\hline & \$ 5.99 & 60 \
\hline & \$ 7.00 & 65 \
\hline & \$ 12.00 & 45 \
\hline & \$ 4.50 & 80 \
\hline & \$ 7.50 & 70 \
\hline & \$ 15.00 & 25 \
\hline & \$ 10.00 & 35 \
\hline & \$ 12.50 & 40 \
\hline & \$ 8.99 & 50\
\hline & \
\hline \text { Mean } &\$8.75&54.50 \
\hline \begin{array} { l } 
\text { Standard } \
\text { Deviation }
\end{array} & \$ 3.63 & 18.33 \
\hline \text { Correlation } & - \mathbf { 0 . 9 2 7 }  \
\hline
\end{array}$$

Based on the data and summary statistics, the intercept of the estimated regression line that Relates the response variable (monthly sales) to the predictor variable (price per pound) is

Accepted Answer

A) 95.459. 
B) .858. 
C) -4.684. 
D) -.858. 
E) -8.999. 
A) 95.459. 
B) .858. 
C) -4.684. 
D) -.858. 
E) -8.999. A

Question 4

Data were collected on monthly sales revenues (in $\$ 1,000 \mathrm {~s}$ ) and monthly advertising expenditures $( \$ 100 \mathrm {~s} )$ for a sample of drug stores. The regression line relating revenues $( \mathrm { Y } )$ to advertising expenditure $( \mathrm { X } )$ is estimated to be $\hat { y } = - 48.3 + 9.00 x$. The correct interpretation of the slope is that for each additional

Accepted Answer

A)  $\$ 1$ spent on advertising, predicted sales revenue increases by $\$ 9,000$. 
B)  $\$ 100$ spent on advertising, predicted sales revenue increases by $\$ 9,000$. 
C)  $\$ 100$ spent on advertising, predicted sales revenue decreases by $\$ 9,000$. 
D)  $\$ 1,000$ in sales revenue, advertising expenditures decrease by $\$ 48.30$. 
E)  $\$ 100$ in sales revenue, advertising expenditures decrease by $\$ 48.30$. 
A)  $\$ 1$ spent on advertising, predicted sales revenue increases by $\$ 9,000$. 
B)  $\$ 100$ spent on advertising, predicted sales revenue increases by $\$ 9,000$. 
C)  $\$ 100$ spent on advertising, predicted sales revenue decreases by $\$ 9,000$. 
D)  $\$ 1,000$ in sales revenue, advertising expenditures decrease by $\$ 48.30$. 
E)  $\$ 100$ in sales revenue, advertising expenditures decrease by $\$ 48.30$.

Question 5

Interpret the intercept of your model in context.

Accepted Answer

The intercept of the model is

Question 6

Interpret the slope of your model in context.

Accepted Answer

Slope of the model is 0.010151

Question 7

An article in the Journal of Statistics Education reported the price of diamonds of different sizes in Singapore dollars (SGD). The following table contains a data set that is consistent with this data, adjusted to US dollars in 2004:

-Make a scatterplot and describe the association between the size of the diamond (carat) and the cost (in US dollars).

Accepted Answer

@#IMG-DLM&
There is a strong, positive,

Question 8

Suppose the correlation, $r$, between two variables $x$ and $y$ is $- 0.44$. What would you predict about a $y$ value if the $x$ value is 2 standard deviations above its mean?

Accepted Answer

A)  It will be $.88$ standard deviations below its mean. 
B)  It will be $.88$ standard deviations above its mean. 
C)  It will be 2 standard deviations below its mean. 
D)  It will be $.44$ standard deviations below its mean. 
E)  It will be $.44$ standard deviations above its mean. 
A)  It will be $.88$ standard deviations below its mean. 
B)  It will be $.88$ standard deviations above its mean. 
C)  It will be 2 standard deviations below its mean. 
D)  It will be $.44$ standard deviations below its mean. 
E)  It will be $.44$ standard deviations above its mean.

Question 9

Do you think a linear model is appropriate here? Explain.

Accepted Answer

The answer of Do you think a linear model is...

Question 10

Data were collected on monthly sales revenues (in $\$ 1,000 \mathrm {~s}$ ) and monthly advertising expenditures $( \$ 100 \mathrm {~s} )$ for a sample of drug stores. The regression line relating revenues (Y) to advertising expenditure $( \mathrm { X } )$ is estimated to be $\hat { y } = - 48.3 + 9.00 x$. The predicted sales revenue for a month in which $\$ 1,000$ was spent on advertising is

Accepted Answer

A)  $\$ 50,000$. 
B)  $\$ 851.70$. 
C)  $\$ 8,951.70$. 
D)  $\$ 41,700$. 
E)  $\$ 90,000$. 
A)  $\$ 50,000$. 
B)  $\$ 851.70$. 
C)  $\$ 8,951.70$. 
D)  $\$ 41,700$. 
E)  $\$ 90,000$.

Question 11

Make a scatterplot and describe the association between the year and the
 $$\begin{array} { | c | c | } 
\hline \text { Year } & \text { Rate } \
\hline 1971 & 0.08 \
\hline 1974 & 0.10 \
\hline 1975 & 0.13 \
\hline 1978 & 0.15 \
\hline 1981 & 0.18 \
\hline 1981 & 0.20 \
\hline 1985 & 0.22 \
\hline 1988 & 0.25 \
\hline 1991 & 0.29 \
\hline 1995 & 0.32 \
\hline
\end{array}$$

Accepted Answer

@#IMG-DLM& There is a strong, positive,

Question 12

Interpret the slope of your model in context.

Accepted Answer

The slope of the model is @#LAT-DLM&. The model pr

Question 13

The correlation coefficient between high school grade point average (GPA) and college GPA is 0.560.For a student with a high school GPA that is 2.5 standard deviations above the Mean, we would expect that student to have a college GPA that is ______ the mean.

Accepted Answer

A) 0.56 SD above 
B) 1.94 SD above 
C) 2.5 SD above 
D) equal to 
E) 1.4 SD above 
A) 0.56 SD above 
B) 1.94 SD above 
C) 2.5 SD above 
D) equal to 
E) 1.4 SD above

Question 14

Do you think a linear model is appropriate here? Explain.

Accepted Answer

Yes, a linear model is appropr

Question 15

If the point in the upper left corner of the scatterplot is removed, what will happen to the Correlation (r) and the slope of the line of best fit (b)?

Accepted Answer

A) r will decrease and  b will increase. 
B) r will increase and b will decrease. 
C) Both will decrease. 
D) Both will increase. 
E) They will not change. 
A) r will decrease and  b will increase. 
B) r will increase and b will decrease. 
C) Both will decrease. 
D) Both will increase. 
E) They will not change.

Question 16

An article in the Journal of Statistics Education reported the price of diamonds of different sizes in Singapore dollars (SGD). The following table contains a data set that is consistent with this data, adjusted to US dollars in 2004:

-Create a model to predict diamond costs from the size of the diamond.

Accepted Answer

The regression equat

Question 17

A small independent organic food store offers a variety of specialty coffees.To determine Whether price has an impact on sales, the managers kept track of how many pounds of each Variety of coffee were sold last month.
 $$\begin{array} { | l | l | l | } 
\hline \text { Mean } & \$ 8.75 & 54.50 \
\hline \begin{array} { c } 
\text { Standard } \
\text { Deviation }
\end{array} & \$ 3.63 & 18.33 \
\hline \text { Correlation } & - \mathbf { 0 . 9 2 7 } & \
\hline
\end{array}$$
Based on the summary statistics shown below, what percent of the variability in the number of pounds of coffee sold per week can be explained by price?

Accepted Answer

A) 95.47% 
B) 100% 
C) 85.9% 
D) 55.6% 
E) 4.68% 
A) 95.47% 
B) 100% 
C) 85.9% 
D) 55.6% 
E) 4.68%

Question 18

What is the correlation between year and postal rate?

Accepted Answer

The correlation, @#LAT-DLM&, is @#LAT-DLM&. Since

Question 19

A small independent organic food store offers a variety of specialty coffees.To determine Whether price has an impact on sales, the managers kept track of how many pounds of each Variety of coffee were sold last month.
 $$\begin{array} { | l | l | l | } 
\hline & \text { PRICE PER POUND } & \text { POUNDS SOLD } \
\hline & \$ 3.99 & 75 \
\hline & \$ 5.99 & 60 \
\hline & \$ 7.00 & 65 \
\hline & \$ 12.00 & 45 \
\hline & \$ 4.50 & 80 \
\hline & \$ 7.50 & 70 \
\hline & \$ 15.00 & 25 \
\hline & \$ 10.00 & 35 \
\hline & \$ 12.50 & 40 \
\hline & \$ 8.99 & 50\
\hline & \
\hline \text { Mean } &\$8.75&54.50 \
\hline \begin{array} { l } 
\text { Standard } \
\text { Deviation }
\end{array} & \$ 3.63 & 18.33 \
\hline \text { Correlation } & - \mathbf { 0 . 9 2 7 }  \
\hline
\end{array}$$
Based on the data and summary statistics shown below, the slope of the estimated regression
Line that relates the response variable (monthly sales) to the predictor variable (price per
Pound) is

Accepted Answer

A) 95.459. 
B) .858. 
C) -4.681. 
D) -.858. 
E) -8.999. 
A) 95.459. 
B) .858. 
C) -4.681. 
D) -.858. 
E) -8.999.

Question 20

If the point in the upper right corner of this scatterplot is removed from the data set, then What will happen to the slope of the line of best fit (b) and to the correlation (r)?

Accepted Answer

A) b will increase, and r will decrease. 
B) b will decrease, and r will increase. 
C) both will decrease. 
D) both will increase. 
E) both will remain the same. 
A) b will increase, and r will decrease. 
B) b will decrease, and r will increase. 
C) both will decrease. 
D) both will increase. 
E) both will remain the same.

Suppose the correlation, r, between two variables x and y is -0.44.What percentage of the Variability in y cannot be explained by x?

Interpret the intercept of your model in context.

Interpret the slope of your model in context.

Suppose the correlation, $r$ , between two variables $x$ and $y$ is $- 0.44$ . What would you predict about a $y$ value if the $x$ value is 2 standard deviations above its mean?

Do you think a linear model is appropriate here? Explain.

Make a scatterplot and describe the association between the year and the Year Rate 1971 0.08 1974 0.10 1975 0.13 1978 0.15 1981 0.18 1981 0.20 1985 0.22 1988 0.25 1991 0.29 1995 0.32

Interpret the slope of your model in context.

The correlation coefficient between high school grade point average (GPA) and college GPA is 0.560.For a student with a high school GPA that is 2.5 standard deviations above the Mean, we would expect that student to have a college GPA that is ______ the mean.

Do you think a linear model is appropriate here? Explain.

If the point in the upper left corner of the scatterplot is removed, what will happen to the Correlation (r) and the slope of the line of best fit (b)?

What is the correlation between year and postal rate?

If the point in the upper right corner of this scatterplot is removed from the data set, then What will happen to the slope of the line of best fit (b) and to the correlation (r)?

Stats Starts Here

Displaying and Describing Data

Relationships Between Categorical Variablescontingency Tables

Understanding and Comparing Distributions

The Standard Deviation As a Ruler and the Normal Model

Scatterplots, Association, and Correlation

Regression Wisdom

Multiple Regression

Sample Surveys

Experiments and Observational Studies

From Randomness to Probability

Sampling Distribution Models and Confidence Intervals for Proportions

Confidence Intervals for Means

Testing Hypotheses

More About Tests and Intervals

Comparing Groupspaired

Samples and Blocks

Comparing Counts

Filters

Exam 7: Linear Regression

Suppose the correlation, r, between two variables x and y is -0.44.What percentage of the Variability in y cannot be explained by x?

Interpret the intercept of your model in context.

Interpret the slope of your model in context.

Suppose the correlation, rrr , between two variables xxx and yyy is −0.44- 0.44−0.44 . What would you predict about a yyy value if the xxx value is 2 standard deviations above its mean?

Do you think a linear model is appropriate here? Explain.

Make a scatterplot and describe the association between the year and the Year Rate 1971 0.08 1974 0.10 1975 0.13 1978 0.15 1981 0.18 1981 0.20 1985 0.22 1988 0.25 1991 0.29 1995 0.32

Interpret the slope of your model in context.

The correlation coefficient between high school grade point average (GPA) and college GPA is 0.560.For a student with a high school GPA that is 2.5 standard deviations above the Mean, we would expect that student to have a college GPA that is ______ the mean.

Do you think a linear model is appropriate here? Explain.

If the point in the upper left corner of the scatterplot is removed, what will happen to the Correlation (r) and the slope of the line of best fit (b)?

What is the correlation between year and postal rate?

If the point in the upper right corner of this scatterplot is removed from the data set, then What will happen to the slope of the line of best fit (b) and to the correlation (r)?

Stats Starts Here

Displaying and Describing Data

Relationships Between Categorical Variablescontingency Tables

Understanding and Comparing Distributions

The Standard Deviation As a Ruler and the Normal Model

Scatterplots, Association, and Correlation

Regression Wisdom

Multiple Regression

Sample Surveys

Experiments and Observational Studies

From Randomness to Probability

Sampling Distribution Models and Confidence Intervals for Proportions

Confidence Intervals for Means

Testing Hypotheses

More About Tests and Intervals

Comparing Groupspaired

Samples and Blocks

Comparing Counts

Filters

Suppose the correlation, $r$ , between two variables $x$ and $y$ is $- 0.44$ . What would you predict about a $y$ value if the $x$ value is 2 standard deviations above its mean?