Zaragoza Alvarado GA. Chapter 4. Grouping to Understand: How to Analyze Data Presented in Intervals. In: Descriptive statistics manual. Definition and exercises [Internet]. AG Editor; 2025 [cited 2025 Dec. 10]. pp. 44-8. Available from: https://books.ageditor.org/index.php/books/catalog/book/978-628-97230-1-4/chapter/15