[a20201109]

Thank you! In the 2019 readability study, the things that did not affect readability (null effects) are at least as interesting as things that did. Organizing Table 4 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6722069/ by reported empirical support:

Null effect:

- Ensure high luminance contrast between text and background

- Avoid using italics

- Use bolding to highlight

- Avoid underlining large blocks of text

- Use a plain, evenly spaced sans serif font

Partial:

- Avoid formatting texts in large-width columns

Yes:

- Limit the amount of content on a page

- Use a minimum of text size 12 pt or 14 pt

- Keep the between-line spacing of 1.5 point

- Use section headings

- Use left-justified text with ragged right edge