1-year-long website A/B test of controversarial typographic choices of indenting & justifying paragraphs: a fairly precise null result. No design change was made.
A core typographic decision for web pages is whether to separate paragraphs using newlines, or indentation; and whether to use ragged-right or fully-justified text. Gwern.net defaults to book-like indentation + justified text; however, most websites do the opposite, and some readers have criticized the Gwern.net style.
To test whether the style has any important effect on readers, I run an A/B test on Gwern.net, randomly testing each day one of the 4 possible combinations, for 318 days (2022-09-27–10m2023-08-10) over 719,549
Analysis finds ~0 effect on page-views, with the effects of indentation/justification being far from statistically-significant or a posteriori probable.
So, I decided to not change the typography.