Tidy Data

Tidy data is a standard, predictable way of laying out a table: each row is one observation, each column is one variable, and each cell holds a single value. For example, a tidy table of exam results has one row per student-exam, with columns like student, subject, and score.

Most analysis and plotting tools expect tidy data, so getting your table into this shape early saves enormous effort later. A common mismatch is a spreadsheet that buries variables in column headers (a separate column for each month) or crams two facts into one cell (“12/85” for height and weight) — both need reshaping before they count as tidy.