Measurement and Sampling Flashcards
what are variables?
something that varies
what does “constant” mean?
something that is fixed/does not change
what is a quantitative measurement?
the use of number to describe a property of an object or event
what is measurement?
the use of number to describe something that happens (or doesn’t happen) in the world
what are examples of measured things?
lecture attendance
temperature
clicks on a website
product units sold
brand reputation perceptions
what are examples of measurement acts?
taking a baby’s temp.
asking question on a survey
counting the number of likes on a tweet
what are the four levels of variable measurement?
(NOIR) nominal, ordinal, interval, ratio
what are the characteristics for nominal (or “categorical”) variables?
- numbers serve as tags or labels
- numbers are not placed on a meaningful scale
- higher/lower number doesn’t mean anything
- membership is both all inclusive and mutually exclusive
what are nominal variables with only two levels called?
dichotomous or binary nominal variable
T or F: This is an example of a nominal variable
Biological sex [1=male, 0=female]
True
What are the characteristics of ordinal variables?
- possible values are meaningfully ordered
- variables do not establish the numeric difference between data points
- indicate that only one data point is ranked higher or lower than another
- distance between number is not set or consistent
T or F: this is an example of ordinal variables
rate teacher effectiveness as excellent (5), good (4), average (3), poor (2) or unsatisfactory (1)
True
what are characteristics of interval variables?
- measured along a scale
- each position is equidistant from other scale points
how is an interval level of measurement achieved?
- if the categories of a variable can be ranked-order
- if the measurements for all the cases are expressed in the same units
T or F: This is an example of interval variables
GPA Scores: a 3.0 is exactly 0.5 GPA points below a 3.5
True
what is a ratio variable?
interval variables with a natural zero point
what does natural zero point mean?
the zero means “none of something”
T or F: this is an example of an interval variable
Distance: two things can be zero inches apart
True
True or False: Nominal attributes are only named, and are the weakest variable
True
T or F: Ordinal attributes can be ordered
True