Neil Irwin, The New York Times:

When something falls by 10 percent and then rises by 10 percent, it might seem as if it ends up back where it started. But that’s not how the math works.

A 10 percent drop from 100 to 90, followed by a 10 percent gain, would return it only to 99. With bigger swings, those effects become more striking. A 40 percent drop followed by a 40 percent gain would result in a quantity 16 percent below the starting point.

Tulisan Irwin mengingatkan kita bagaimana penggunaan persentase dalam menampilkan data dapat membuat orang-orang salah memahami data. Ia juga menekankan bahwa kita perlu berhati-hati ketika mengunyah data-data yang beredar, terutama di saat keadaan sedang tidak normal seperti sekarang ini.