BNAL EXAM 2 13-14 QUESTIONS AND VERIFIED
ANSWERS
The Y-intercept ( b 0) represents the
predicted value of Y when X = 0.
change in estimated Y per unit change in X.
predicted value of Y.
variation around the sample regression line. - Answers - predicted value of Y when X =
0
The slope ( b 1) represents
predicted value of Y when X = 0.
the estimated average change in Y per unit change in X.
the predicted value of Y.
variation around the line of regression. - Answers - the estimated average change in Y
per unit change in X.
The Chancellor of a university has commissioned a team to collect data on students'
GPAs and the amount of time they spend bar hopping every week (measured in
minutes). He wants to know if imposing much tougher regulations on all campus bars to
make it more difficult for students to spend time in any campus bar will have a
significant impact on general students' GPAs. His team should use a t test on the slope
of the population regression. (T/F) - Answers - True
TABLE 13-6
The following Excel tables are obtained when "Score received on an exam (measured in
percentage points)" ( Y) is regressed on "percentage attendance" ( X) for 22 students in
a Statistics for Business and Economics course.
Referring to Table 13-6, which of the following statements is true?
14.26% of the total variability in score received can be explained by percentage
attendance.
14.2% of the total variability in percentage attendance can be explained by score
received.
2% of the total variability in score received can be explained by percentage attendance.
2% of the total variability in percentage attendance can be explained by score received.
- Answers - 2% of the total variability in score received can be explained by percentage
attendance.
,TABLE 13-6
The following Excel tables are obtained when "Score received on an exam (measured in
percentage points)" ( Y) is regressed on "percentage attendance" ( X) for 22 students in
a Statistics for Business and Economics course.
Referring to Table 13-6, which of the following statements is true?
If attendance increases by 0.341%, the estimated mean score received will increase by
1 percentage point.
If attendance increases by 1%, the estimated mean score received will increase by
39.39 percentage points.
If attendance increases by 1%, the estimated mean score received will increase by
0.341 percentage points.
If the score received increases by 39.39%, the estimated mean attendance will go up
by 1%. - Answers - If attendance increases by 1%, the estimated mean score received
will increase by 0.341 percentage points.
The residuals represent
the difference between the actual Y values and the mean of Y.
the difference between the actual Y values and the predicted Y values.
the square root of the slope.
the predicted value of Y for the average X value. - Answers - the difference between
the actual Y values and the predicted Y values
The strength of the linear relationship between two numerical variables may be
measured by the
scatter plot.
coefficient of correlation.
slope.
Y-intercept. - Answers - coefficient of correlation.
In a simple linear regression problem, r and b 1
may have opposite signs.
must have the same sign.
must have opposite signs.
are equal. - Answers - must have the same sign.
A computer software developer would like to use the number of downloads (in
thousands) for the trial version of his new shareware to predict the amount of revenue
(in thousands of dollars) he can make on the full version of the new shareware.
Following is the output from a simple linear regression along with the residual plot and
normal probability plot obtained from a data set of 30 different sharewares that he has
developed:
, Referring to table 13-11, which of the following is the correct interpretation for the slope
coefficient?
For each decrease of 1 thousand downloads, the expected revenue is estimated to
increase by $ 3.7297 thousands.
For each increase of 1 thousand downloads, the expected revenue is estimated to
increase by $ 3.7297 thousands.
For each decrease of 1 thousand dollars in expected revenue, the expected number of
downloads is estimated to increase by 3.7297 thousands.
For each increas - Answers - For each increase of 1 thousand downloads, the
expected revenue is estimated to increase by $ 3.7297 thousands.
TABLE 13-11
A computer software developer would like to use the number of downloads (in
thousands) for the trial version of his new shareware to predict the amount of revenue
(in thousands of dollars) he can make on the full version of the new shareware.
Following is the output from a simple linear regression along with the residual plot and
normal probability plot obtained from a data set of 30 different sharewares that he has
developed:
Referring to Table 13-11, which of the following is the correct interpretation for the
coefficient of determination?
Answers:
74.67% of the variation in revenue can be explained by the variation in the number of
downloads.
75.54% of the variation in revenue can be explained by the variation in the number of
downloads.
74.67% of the variation in the number of downloads can be explained by the variation in
revenue.
75.54% of the variation in the number of downloads can - Answers - 75.54% of the
variation in revenue can be explained by the variation in the number of downloads.
ANSWERS
The Y-intercept ( b 0) represents the
predicted value of Y when X = 0.
change in estimated Y per unit change in X.
predicted value of Y.
variation around the sample regression line. - Answers - predicted value of Y when X =
0
The slope ( b 1) represents
predicted value of Y when X = 0.
the estimated average change in Y per unit change in X.
the predicted value of Y.
variation around the line of regression. - Answers - the estimated average change in Y
per unit change in X.
The Chancellor of a university has commissioned a team to collect data on students'
GPAs and the amount of time they spend bar hopping every week (measured in
minutes). He wants to know if imposing much tougher regulations on all campus bars to
make it more difficult for students to spend time in any campus bar will have a
significant impact on general students' GPAs. His team should use a t test on the slope
of the population regression. (T/F) - Answers - True
TABLE 13-6
The following Excel tables are obtained when "Score received on an exam (measured in
percentage points)" ( Y) is regressed on "percentage attendance" ( X) for 22 students in
a Statistics for Business and Economics course.
Referring to Table 13-6, which of the following statements is true?
14.26% of the total variability in score received can be explained by percentage
attendance.
14.2% of the total variability in percentage attendance can be explained by score
received.
2% of the total variability in score received can be explained by percentage attendance.
2% of the total variability in percentage attendance can be explained by score received.
- Answers - 2% of the total variability in score received can be explained by percentage
attendance.
,TABLE 13-6
The following Excel tables are obtained when "Score received on an exam (measured in
percentage points)" ( Y) is regressed on "percentage attendance" ( X) for 22 students in
a Statistics for Business and Economics course.
Referring to Table 13-6, which of the following statements is true?
If attendance increases by 0.341%, the estimated mean score received will increase by
1 percentage point.
If attendance increases by 1%, the estimated mean score received will increase by
39.39 percentage points.
If attendance increases by 1%, the estimated mean score received will increase by
0.341 percentage points.
If the score received increases by 39.39%, the estimated mean attendance will go up
by 1%. - Answers - If attendance increases by 1%, the estimated mean score received
will increase by 0.341 percentage points.
The residuals represent
the difference between the actual Y values and the mean of Y.
the difference between the actual Y values and the predicted Y values.
the square root of the slope.
the predicted value of Y for the average X value. - Answers - the difference between
the actual Y values and the predicted Y values
The strength of the linear relationship between two numerical variables may be
measured by the
scatter plot.
coefficient of correlation.
slope.
Y-intercept. - Answers - coefficient of correlation.
In a simple linear regression problem, r and b 1
may have opposite signs.
must have the same sign.
must have opposite signs.
are equal. - Answers - must have the same sign.
A computer software developer would like to use the number of downloads (in
thousands) for the trial version of his new shareware to predict the amount of revenue
(in thousands of dollars) he can make on the full version of the new shareware.
Following is the output from a simple linear regression along with the residual plot and
normal probability plot obtained from a data set of 30 different sharewares that he has
developed:
, Referring to table 13-11, which of the following is the correct interpretation for the slope
coefficient?
For each decrease of 1 thousand downloads, the expected revenue is estimated to
increase by $ 3.7297 thousands.
For each increase of 1 thousand downloads, the expected revenue is estimated to
increase by $ 3.7297 thousands.
For each decrease of 1 thousand dollars in expected revenue, the expected number of
downloads is estimated to increase by 3.7297 thousands.
For each increas - Answers - For each increase of 1 thousand downloads, the
expected revenue is estimated to increase by $ 3.7297 thousands.
TABLE 13-11
A computer software developer would like to use the number of downloads (in
thousands) for the trial version of his new shareware to predict the amount of revenue
(in thousands of dollars) he can make on the full version of the new shareware.
Following is the output from a simple linear regression along with the residual plot and
normal probability plot obtained from a data set of 30 different sharewares that he has
developed:
Referring to Table 13-11, which of the following is the correct interpretation for the
coefficient of determination?
Answers:
74.67% of the variation in revenue can be explained by the variation in the number of
downloads.
75.54% of the variation in revenue can be explained by the variation in the number of
downloads.
74.67% of the variation in the number of downloads can be explained by the variation in
revenue.
75.54% of the variation in the number of downloads can - Answers - 75.54% of the
variation in revenue can be explained by the variation in the number of downloads.
