Is correlation a percentage? The Pearson correlation coefficient ranges from -1 to 1. Oftentimes, people take this number, multiply it by 100 and call it

-17.3% correlation

or

63% correlation

I was once dinged by reviewers for this, in a STEM journal. Is this really a mistake?

Examples of real-world usage:
Book: Spurious Correlations:

Textbook: Clear-Sighted Statistics: Module 18: Linear Correlation and Regression:


It’s wrong, and if a reviewer wants to tell you to change it, you have no argument. I would not, however, consider that to be more than a typo (minor revision), even if I said it should be changed.
I see an argument that it’s just a slang that perhaps has no place in formal writing like a scientific article but is fine for casual discussions. However, squaring the correlation has an interpretation as a proportion or percentage (it’s $R^2$ in a regression involving your two variables), so I think I do not like such a slang. If you mentioned having a correlation of $81\%$, that could correspond to $r=0.81$, $r=0.9$, or $r=-0.9$.
