Data tables are set up so that observations form rows, variables
form columns, and values reside in cells:
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It is important to differentiate between variables, values, and observations. Variables represent the thing being measured (e.g., AGE), while values represent realized measurements (e.g., 31). An observation is usually characterized by multiple variables (e.g., AGE, SEX, HEIGHT).
Categorical variable - data comprise named categories (e.g., EYECOLOR classified as brown, blue, or other); syn: qualitative variable, nominal variable.
Ordinal variable - data comprise categories which can be ordered from low to high (e.g., AGREEMENT classified as strongly agree, agree, neutral, disagree, or strongly disagree).