4  Descriptive Statistics

Helps in describing and understanding the center, spread, and shape of a variable.

By the way, what is a variable?

A variable is a quantity or category recorded for each observational unit (e.g., subject, sample, ASV). Formally, a variable is a function \(X: \Omega \to S\) mapping units to a set of possible values \(S\) (numbers, categories, dates, etc.).

Observation/unit: the entity measured (e.g., one stool sample).

Feature/predictor: an explanatory variable (e.g., age, batch, sequencing depth).

Outcome/response: the variable we primarily seek to explain (e.g., disease status, alpha diversity).

Identifier (ID): a label (e.g., sample ID). IDs are not variables for analysis.