STT 231: Exam 1 Questions with 100% Correct
Answers
Data is made up of ______
Observational units
Variable
Any characteristic (or value) recorded for each case
Categorical variable
Identify a case as a measure of a group, placing each case into exactly one of two or more
groups, called levels.
Example: Year (first year, second year, third year...)
Nominal variable
Groups with no logical arrangement
Example: (eye color, major, gender)
Ordinal Variable
Groups with logical arrangement
Example: (first year, second year, third year)
Numerical variable
Measure a numerical quantity for each use.
Example: Credits (0,1,2,3)
Discrete variable
, Limited values in a variables domain. No in between numbers
Example: (Number of students in a class, number of siblings...)
Continuous variable
Any value in a variables domain.
Example: (98.64, 12.347 seconds)
Why are average and proportion not variables when considering yourself to be the
observational unit.
They don't describe the characteristic of a single student. Instead, they summarize the
combined characteristics of all students simultaneously. These are actually statistics.
If you changed the observational unit to be "classes at MSU" then they would be variables.
Explanatory Variable
A variable manipulated by the researcher
Response Variable
What tends to change as a result
What relationship do the explanatory and response variable share?
Casual
Central tendency
Describes the "balancing point" of the data.
Variability
Describing the spread or dispersion of data from the center.
Answers
Data is made up of ______
Observational units
Variable
Any characteristic (or value) recorded for each case
Categorical variable
Identify a case as a measure of a group, placing each case into exactly one of two or more
groups, called levels.
Example: Year (first year, second year, third year...)
Nominal variable
Groups with no logical arrangement
Example: (eye color, major, gender)
Ordinal Variable
Groups with logical arrangement
Example: (first year, second year, third year)
Numerical variable
Measure a numerical quantity for each use.
Example: Credits (0,1,2,3)
Discrete variable
, Limited values in a variables domain. No in between numbers
Example: (Number of students in a class, number of siblings...)
Continuous variable
Any value in a variables domain.
Example: (98.64, 12.347 seconds)
Why are average and proportion not variables when considering yourself to be the
observational unit.
They don't describe the characteristic of a single student. Instead, they summarize the
combined characteristics of all students simultaneously. These are actually statistics.
If you changed the observational unit to be "classes at MSU" then they would be variables.
Explanatory Variable
A variable manipulated by the researcher
Response Variable
What tends to change as a result
What relationship do the explanatory and response variable share?
Casual
Central tendency
Describes the "balancing point" of the data.
Variability
Describing the spread or dispersion of data from the center.
