1. Foundational Definitions
Foundations I
Foundational Definitions

2. Variable Types Quantitative … measurements or counts
Categorical (Qualitative) … group membership
Variable Types

3. Variable Types Quantitative … measurements or counts
Continuous
a potential value exists between all pairs of values
e.g., amount of rainfall
Discrete
a potential value does not exist between all pairs of values
typically (but not always) counts of things
e.g., number of days that it rained in a year
Categorical (Qualitative) … group membership
Variable Types

4. Variable Types Quantitative … measurements or counts
Categorical (Qualitative) … group membership
Ordinal
a natural order exists among the categories
e.g., cloud cover (sunny, part. sunny, part. cloudy, cloudy)
Nominal
no natural order exists among the categories
e.g., type of cloud (cumulus, cirrus, …)
Variable Types

5. Important Distinction
What are the possible answers for the following two question types?
What type of variable is blah-blah-blah?
What type of variability explains the fact that yada-yada-yada?
Foundations I