STAT 121 FINAL EXAM UPDATED QUESTIONS AND ANSWERS
A study investigated whether a student's grade in STAT 121 could be predicted from their ACT math
score. What are the response and explanatory variables?
a) resp = stat grade
expl. = ACT math
b) resp = ACT math
expl = stat grade - CORRECT ANSWER✅✅a) resp = stat grade
expl. = ACT math
What is the visual display tool for a Q --> Q case? - CORRECT ANSWER✅✅scatterplot
What are the numerical study tools for a Q --> Q case? - CORRECT ANSWER✅✅correlation, regression
line
What are the goals for a Q --> Q case? - CORRECT ANSWER✅✅characterize the nature of the
relationship
predict one variable from another
investigate if changes in one variable cause changes in another
If a data set consists of 2 variables measured on each of 20 individuals, how many dots are in the
scatterplot?
a) 10
b) 20
c) 30
d) 40 - CORRECT ANSWER✅✅b) 20
What are the 3 ways to assess a scatterplot? - CORRECT ANSWER✅✅direction
form
,strength
What are the 3 classes or ways you can categorize the form of a given scatterplot? - CORRECT
ANSWER✅✅linear
nonlinear
non-distinguishable
What is considered an outlier? - CORRECT ANSWER✅✅any point that doesn't follow the relationship or
form in the data
T or F: Everyone will draw the same conclusions about form, direction, and strength from a scatter plot?
- CORRECT ANSWER✅✅FALSE
T or F: a Q --> Q relationship only works for linear relationships? - CORRECT ANSWER✅✅TRUE
In a linear relationship you need a measure of strength that is ________ , __________ , and
______________ . - CORRECT ANSWER✅✅objective
numeric
not fooled by scales of information
What is the symbol for correlation coefficient? - CORRECT ANSWER✅✅r
What is the correlation coefficient? - CORRECT ANSWER✅✅a numeric, scale invariant measure of
strength and direction of linear relationship between 2 quantitative variables
T or F: a numeric, scale invariant measure of strength and direction of a relationship between 2
quantitative variables ONLY works for a linear relationship - CORRECT ANSWER✅✅TRUE
In order for their to be a perfect negative relationship (in a Q --> Q case )what needs to be the case? -
CORRECT ANSWER✅✅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? -
CORRECT ANSWER✅✅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? - CORRECT ANSWER✅✅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? - CORRECT ANSWER✅✅points will be more spread out on the positive slope
What does it mean when r = 0? - CORRECT ANSWER✅✅there is no linear relationship
What does it mean when r > -1, but < 0? - CORRECT ANSWER✅✅intermediate negative relationship
What does it mean when r > 0 but < 1? - CORRECT ANSWER✅✅intermediate positive relationship
What does it mean when r = 1? - CORRECT ANSWER✅✅perfect positive relationship
What does it mean when r = -1? - CORRECT ANSWER✅✅perfect negative relationship
Which numbers will the value of r always fall between? - CORRECT ANSWER✅✅1 & -1
What are the properties of r? - CORRECT ANSWER✅✅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 - CORRECT ANSWER✅✅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 - CORRECT ANSWER✅✅c) sing of r denotes direction of relationship
T or F: r ONLY works for quantitative variables - CORRECT ANSWER✅✅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 - CORRECT ANSWER✅✅c) r does not change if the units
of x or y change
A study investigated whether a student's grade in STAT 121 could be predicted from their ACT math
score. What are the response and explanatory variables?
a) resp = stat grade
expl. = ACT math
b) resp = ACT math
expl = stat grade - CORRECT ANSWER✅✅a) resp = stat grade
expl. = ACT math
What is the visual display tool for a Q --> Q case? - CORRECT ANSWER✅✅scatterplot
What are the numerical study tools for a Q --> Q case? - CORRECT ANSWER✅✅correlation, regression
line
What are the goals for a Q --> Q case? - CORRECT ANSWER✅✅characterize the nature of the
relationship
predict one variable from another
investigate if changes in one variable cause changes in another
If a data set consists of 2 variables measured on each of 20 individuals, how many dots are in the
scatterplot?
a) 10
b) 20
c) 30
d) 40 - CORRECT ANSWER✅✅b) 20
What are the 3 ways to assess a scatterplot? - CORRECT ANSWER✅✅direction
form
,strength
What are the 3 classes or ways you can categorize the form of a given scatterplot? - CORRECT
ANSWER✅✅linear
nonlinear
non-distinguishable
What is considered an outlier? - CORRECT ANSWER✅✅any point that doesn't follow the relationship or
form in the data
T or F: Everyone will draw the same conclusions about form, direction, and strength from a scatter plot?
- CORRECT ANSWER✅✅FALSE
T or F: a Q --> Q relationship only works for linear relationships? - CORRECT ANSWER✅✅TRUE
In a linear relationship you need a measure of strength that is ________ , __________ , and
______________ . - CORRECT ANSWER✅✅objective
numeric
not fooled by scales of information
What is the symbol for correlation coefficient? - CORRECT ANSWER✅✅r
What is the correlation coefficient? - CORRECT ANSWER✅✅a numeric, scale invariant measure of
strength and direction of linear relationship between 2 quantitative variables
T or F: a numeric, scale invariant measure of strength and direction of a relationship between 2
quantitative variables ONLY works for a linear relationship - CORRECT ANSWER✅✅TRUE
In order for their to be a perfect negative relationship (in a Q --> Q case )what needs to be the case? -
CORRECT ANSWER✅✅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? -
CORRECT ANSWER✅✅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? - CORRECT ANSWER✅✅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? - CORRECT ANSWER✅✅points will be more spread out on the positive slope
What does it mean when r = 0? - CORRECT ANSWER✅✅there is no linear relationship
What does it mean when r > -1, but < 0? - CORRECT ANSWER✅✅intermediate negative relationship
What does it mean when r > 0 but < 1? - CORRECT ANSWER✅✅intermediate positive relationship
What does it mean when r = 1? - CORRECT ANSWER✅✅perfect positive relationship
What does it mean when r = -1? - CORRECT ANSWER✅✅perfect negative relationship
Which numbers will the value of r always fall between? - CORRECT ANSWER✅✅1 & -1
What are the properties of r? - CORRECT ANSWER✅✅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 - CORRECT ANSWER✅✅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 - CORRECT ANSWER✅✅c) sing of r denotes direction of relationship
T or F: r ONLY works for quantitative variables - CORRECT ANSWER✅✅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 - CORRECT ANSWER✅✅c) r does not change if the units
of x or y change
