5  Classifying Variables

5.1 Name That Type for $400

Before you answer, use the module’s main question: what are these values actually doing?
Are they naming a group, showing order, counting whole units, or measuring along a scale?

## A column labeled `District` has values 1, 2, 3, and 4. What type of variable is it most likely to be? > The numbers look numeric, but here they are acting as IDs for places. 1. [x] Nominal 1. [ ] Ordinal 1. [ ] Count (discrete) 1. [ ] Measurement (continuous) ## A symptom scale recorded as `none / mild / moderate / severe` is usually what type of variable? > The order matters, but the spacing between levels is not guaranteed to be equal. 1. [ ] Nominal 1. [x] Ordinal 1. [ ] Count (discrete) 1. [ ] Measurement (continuous) ## Number of clinic visits in the last 12 months is usually what type of variable? > This is a count of whole events. 1. [ ] Nominal 1. [ ] Ordinal 1. [x] Count (discrete) 1. [ ] Measurement (continuous) ## Systolic blood pressure measured in mmHg is usually what type of variable? > This is a measurement that could, in principle, be recorded more precisely. 1. [ ] Nominal 1. [ ] Ordinal 1. [ ] Count (discrete) 1. [x] Measurement (continuous) ## Educational attainment such as `high school / some college / bachelor's / graduate degree` is usually what type of variable? > There is a real order, but the distance between levels is not a fixed numeric unit. 1. [ ] Nominal 1. [x] Ordinal 1. [ ] Count (discrete) 1. [ ] Measurement (continuous) ## A survey response recorded as `Refused`, `Unknown`, and `Not applicable` should usually be treated as what type of variable? > These are categories about the record’s relationship to the question, not an amount. 1. [x] Nominal 1. [ ] Ordinal 1. [ ] Count (discrete) 1. [ ] Measurement (continuous) ## Age recorded in whole years is trickier than it first looks. In most simple datasets, how is it best treated? > Age is conceptually time lived, but the recorded version here is in whole-year steps. 1. [ ] Nominal 1. [ ] Ordinal 1. [x] Count (discrete) 1. [ ] Measurement (continuous) ## Age grouped into bands such as `0–5`, `6–10`, and `11–15` is what type of variable in that grouped form? > The grouped version is no longer acting like a direct measurement. 1. [ ] Nominal 1. [x] Ordinal 1. [ ] Count (discrete) 1. [ ] Measurement (continuous) ## Calories on a nutrition label are usually shown as whole numbers. What type are calories really? > The label rounds them, but the underlying thing is still a measure of energy. 1. [ ] Nominal 1. [ ] Ordinal 1. [ ] Count (discrete) 1. [x] Measurement (continuous) ## You ate 3 oranges this week. In that unit, what type of variable is “number of orange slices eaten”? > You are counting whole oranges. 1. [ ] Nominal 1. [ ] Ordinal 1. [x] Count (discrete) 1. [ ] Measurement (continuous) ## Now suppose you switch from counting oranges to measuring orange mass in grams. What type is it now? > The unit changed from counting objects to measuring an amount. 1. [ ] Nominal 1. [ ] Ordinal 1. [ ] Count (discrete) 1. [x] Measurement (continuous) ## Which question best captures the reflex this whole module is trying to build? > This is the habit that should come before summaries, graphs, or tests. 1. [ ] “Can I average this?” 1. [ ] “What software command should I use?” 1. [x] “What kind of thing do these values represent?” 1. [ ] “Does this column contain numbers?”