STAT 121 Final Exam Common Questions
Verified Answers
In order for their to be a perfect negative relationship (in a Q --> Q case )what needs to be
the case?
EVERY SINGLE point needs to fall exactly on the negative slope line
In order for their to be a perfect positive relationship (in a Q --> Q case )what needs to be
the case?
EVERY SINGLE point needs to fall exactly on the positive slope line
In order for their to be an intermediate negative relationship (in a Q --> Q case )what needs to
be the case?
points will be more spread out on the negative slope
In order for their to be an intermediate positive relationship (in a Q --> Q case )what needs
to be the case?
points will be more spread out on the positive slope
What does it mean when r = 0?
there is no linear relationship
What does it mean when r > -1, but < 0?
intermediate negative relationship
What does it mean when r > 0 but < 1?
intermediate positive relationship
,What does it mean when r = 1?
perfect positive relationship
What does it mean when r = -1?
perfect negative relationship
Which numbers will the value of r always fall between?
1&-1
What are the properties of r?
ranges between 1 & -1
NO units of measurement
when the units of measurement change for either of the variables, the value of r does
not change
NO distinction between response and explanatory variable
heavily influenced by outliers
What are the following properties attached to?
ranges between 1 & -1
NO units of measurement
when the units of measurement change for either of the variables, the value of r does
not change
,NO distinction between response and explanatory variable
heavily influenced by outliers
r
Which of the following statements is true?
a) r works for quantitative or categorical variables
b) r makes a distinction between explanatory and response variables
c) sing of r denotes direction of relationship
d) r could be -1.5
c) sing of r denotes direction of relationship
T or F: r ONLY works for quantitative variables
TRUE
Which of the following statements is true?
a) r can be used to describe the strength of curved relationships
b) r is resistant to outliers
c) r does not change if the units of x or y change
d) r is a complete summary of 2-variable data
c) r does not change if the units of x or y change
Which of the following statements is false?
a) r cannot be used to describe the strength of curved relationships
b) r is affected by outliers
c) r does not change if the units of x or y change
d) r is a complete summary of 2-variable data
d) r is a complete summary of 2-variable data
What adds a measure of strength of the relationship in a Q-->Q relationship?
, r - correlation coefficient
For the data displayed in the following scatterplot, is it appropriate to calculate
the correlation?
image A
A. Yes, because the data is bivariate.
B. Yes, because the relationship is linear.
C. No, because the sample size is not large enough.
D. No, because the relationship does not appear linear.
B. Yes, because the relationship is linear.
Referring to question 1, how would you describe the form, direction, and strength of the
scatterplot?
image A
A. Linear, negative, moderately strong
B. Linear, positive, moderately strong
C. Non-linear, negative, weak
D. Non-linear, positive, weak
E. Linear, negative, weak
F. Linear, positive, weak
A. Linear, negative, moderately strong
True or False: If the correlation between x and y is r = 0, then we can say that there is no
relationship of any form between x and y.
FALSE
Verified Answers
In order for their to be a perfect negative relationship (in a Q --> Q case )what needs to be
the case?
EVERY SINGLE point needs to fall exactly on the negative slope line
In order for their to be a perfect positive relationship (in a Q --> Q case )what needs to be
the case?
EVERY SINGLE point needs to fall exactly on the positive slope line
In order for their to be an intermediate negative relationship (in a Q --> Q case )what needs to
be the case?
points will be more spread out on the negative slope
In order for their to be an intermediate positive relationship (in a Q --> Q case )what needs
to be the case?
points will be more spread out on the positive slope
What does it mean when r = 0?
there is no linear relationship
What does it mean when r > -1, but < 0?
intermediate negative relationship
What does it mean when r > 0 but < 1?
intermediate positive relationship
,What does it mean when r = 1?
perfect positive relationship
What does it mean when r = -1?
perfect negative relationship
Which numbers will the value of r always fall between?
1&-1
What are the properties of r?
ranges between 1 & -1
NO units of measurement
when the units of measurement change for either of the variables, the value of r does
not change
NO distinction between response and explanatory variable
heavily influenced by outliers
What are the following properties attached to?
ranges between 1 & -1
NO units of measurement
when the units of measurement change for either of the variables, the value of r does
not change
,NO distinction between response and explanatory variable
heavily influenced by outliers
r
Which of the following statements is true?
a) r works for quantitative or categorical variables
b) r makes a distinction between explanatory and response variables
c) sing of r denotes direction of relationship
d) r could be -1.5
c) sing of r denotes direction of relationship
T or F: r ONLY works for quantitative variables
TRUE
Which of the following statements is true?
a) r can be used to describe the strength of curved relationships
b) r is resistant to outliers
c) r does not change if the units of x or y change
d) r is a complete summary of 2-variable data
c) r does not change if the units of x or y change
Which of the following statements is false?
a) r cannot be used to describe the strength of curved relationships
b) r is affected by outliers
c) r does not change if the units of x or y change
d) r is a complete summary of 2-variable data
d) r is a complete summary of 2-variable data
What adds a measure of strength of the relationship in a Q-->Q relationship?
, r - correlation coefficient
For the data displayed in the following scatterplot, is it appropriate to calculate
the correlation?
image A
A. Yes, because the data is bivariate.
B. Yes, because the relationship is linear.
C. No, because the sample size is not large enough.
D. No, because the relationship does not appear linear.
B. Yes, because the relationship is linear.
Referring to question 1, how would you describe the form, direction, and strength of the
scatterplot?
image A
A. Linear, negative, moderately strong
B. Linear, positive, moderately strong
C. Non-linear, negative, weak
D. Non-linear, positive, weak
E. Linear, negative, weak
F. Linear, positive, weak
A. Linear, negative, moderately strong
True or False: If the correlation between x and y is r = 0, then we can say that there is no
relationship of any form between x and y.
FALSE
