5.1 What is “tidy” data?

Tidy data is where:

• Each column describes a variable.
• Each row describes an observation.
• Each value is a cell.

Figure 5.1: Tidy data. Source

Example of a tidy data:

day	month	year	weight	height
12	4	2020	3.5	48
23	8	2019	2.9	50
9	11	2020	3.8	50

Example of untidy data:

day	month,year	weight	height
12	4,2020	3.5kg	48
23	8,2019	2.9kg	50
9	11,2020	3.8kg	50

Here we introduce some useful functions from the tidyr package to clean up and organize data so as to obtain tidy data that can then be processed more easily.