STT 231 Exam Prep Questions and Answers | 2026
Update | 100% Correct
What makes up a data set?
Data are made up of observational units (cases)
Variable
any characteristic or value recorded for each case; found in columns (vertical)
Observations/Observational Units/Cases
Found in rows (horizontal)
Values
Items that populate a data set
All variables are either ______ or ______
Categorical or numerical
Categorical Variables
Identify a case as a measure of a group, placing each case into exactly one of two or more groups
called levels.
Ex. An MSU student can be classified by their year (first second third...) where these categories
are called levels.
Numerical Variables
,Measure a numerical quantity for each case. Unlike categorical variables, numerical operations
like adding and averaging make sense for these quantitative variables.
Ex. we can record how many credits an MSU student has earned (1,2,3...)
Numerical Variables can be divided into two groups: ____ and____
Discrete and continuous
Numerical discrete variables
can only take on limited values in a variables domain.
Ex. How many siblings do I have? (1,2,3...) but could not say 1.7 siblings.
Numerical Continuous Variables
can take on any value in a variable's domain.
Ex. Height-- could be 52in or 53in or 53.262 in
Categorical variables can be divided into 2 groups: ____ and ____
nominal and ordinal
Categorical Nominal Variables
Variables sort cases into groups that do not have any logical arrangement.
Ex. What soda did you last drink?
, Variables: Sprite, Coke, Faygo
Variables have no logical order or arrangement
Categorical Ordinal Variables
Variables describe variables whose levels have some logical arrangement.
Ex. What was the last size of soda you consumed?
Variables: S,M,L,XL...
These clearly have an order from small to large
Ordinal=Ordered
Don't confuse a discrete measurement of a continuous variable for a variable that is
actually discrete. what is an example of this?
Age is really continuous but in society we round to discrete values. So it is a continuous variable
that could easily be confused for a discrete one.
Statistics
Summaries of variables rather than variables themselves
Why are averages and proportions not variables?
They don't describe a characteristic of a certain observational unit (case), instead the summarize
the combined characteristics of all cases simultaneously.
In the field of statistics, it is important to pay attention to the ______ _______ that make up
your data.
Observational Units
Update | 100% Correct
What makes up a data set?
Data are made up of observational units (cases)
Variable
any characteristic or value recorded for each case; found in columns (vertical)
Observations/Observational Units/Cases
Found in rows (horizontal)
Values
Items that populate a data set
All variables are either ______ or ______
Categorical or numerical
Categorical Variables
Identify a case as a measure of a group, placing each case into exactly one of two or more groups
called levels.
Ex. An MSU student can be classified by their year (first second third...) where these categories
are called levels.
Numerical Variables
,Measure a numerical quantity for each case. Unlike categorical variables, numerical operations
like adding and averaging make sense for these quantitative variables.
Ex. we can record how many credits an MSU student has earned (1,2,3...)
Numerical Variables can be divided into two groups: ____ and____
Discrete and continuous
Numerical discrete variables
can only take on limited values in a variables domain.
Ex. How many siblings do I have? (1,2,3...) but could not say 1.7 siblings.
Numerical Continuous Variables
can take on any value in a variable's domain.
Ex. Height-- could be 52in or 53in or 53.262 in
Categorical variables can be divided into 2 groups: ____ and ____
nominal and ordinal
Categorical Nominal Variables
Variables sort cases into groups that do not have any logical arrangement.
Ex. What soda did you last drink?
, Variables: Sprite, Coke, Faygo
Variables have no logical order or arrangement
Categorical Ordinal Variables
Variables describe variables whose levels have some logical arrangement.
Ex. What was the last size of soda you consumed?
Variables: S,M,L,XL...
These clearly have an order from small to large
Ordinal=Ordered
Don't confuse a discrete measurement of a continuous variable for a variable that is
actually discrete. what is an example of this?
Age is really continuous but in society we round to discrete values. So it is a continuous variable
that could easily be confused for a discrete one.
Statistics
Summaries of variables rather than variables themselves
Why are averages and proportions not variables?
They don't describe a characteristic of a certain observational unit (case), instead the summarize
the combined characteristics of all cases simultaneously.
In the field of statistics, it is important to pay attention to the ______ _______ that make up
your data.
Observational Units
