Science Style Guide: Bullet Points

This post is part of my ongoing scientific style guideline series.

Writing with bullet points (or bullet numbers, letters etc.) has several advantages:

It provides clear guidance to readers.
It forces the writer to think about the structure of what they’re trying to say.
It comes with built-in line breaks, which tends to create shorter, more readable paragraphs.
It breaks the flow of normal prose, which makes reading less monotonous.
It is another channel to communicate emphasis (in addition to italics, bold, caps, subheadings, etc.).

Not everything in a piece of writing should follow point form format. Regular prose, organized in paragraphs, is better for most things. But when you are trying to express something that’s highly structured, like a list of steps (in a recipe, or in an experimental protocol), then not using bulleted lists can work against you.

Science papers being a weirdly conservative genre, bulleted lists are somewhat uncommon in them. Papers will quite often use quasi-point form formats, like (1) having numbers or letters in the middle of a paragraph, like this; (2) using “first,” “second,” “third”; or (3) separating ideas with quasi-titles written in italics or bold, but without a line break.

You see this a lot in figures. Many scientific figures are complex and contain multiple parts. Each part is identified with a letter, as in the following example from the platypus paper:

And the caption will have long explanations separated by very easy to miss letters, like this. (A) The first part of the figure, including some colors and shapes. (B) The second part. Note that this part comes after the first part, and before part C. (C) The third part. I’m running out pointless things to write, but I want this to be a wall of text, so I’m gonna keep writing. (D) Have you lost attention yet? (E) That’s a lot of parts, isn’t it? Funny thing, there’s a limitation of how I do image captions that wouldn’t even let me use bullet points even if I wanted to. (F) At last, the final part. So much information needed to make sense of this picture, right? It’s good to be exhaustive, but there’s no point in making it difficult for readers.

A lot of these habits come, I assume, from the fact that journals used to be available only in print. Space was very limited, and there’s often a lot of scientific information to display, so you’re not going to waste any with bullet points.

Today we don’t have these limitations. Using bullet points where appropriate is nice to your readers, so use them. They’re an easy way to reduce reading friction.

They’re also clearly a Low-Hanging Fruit. Similar to breaking paragraphs, it takes very little work to turn a piece of text into a list, if it’s already presenting the information in something close to a list. (If it isn’t, then bullet points probably won’t work well anyway.) It’s also one of those interventions that can be done almost mechanistically.

Recommendations

Use bullet points liberally when it is appropriate, e.g. for:
- Steps in a process, experiment, protocol, etc.
- Lists of materials used, substances, etc.
- Enumerations (e.g. “the five characteristics of X are : …”)
Nested bullet points (just like the above) can be useful, but don’t overuse them.
- At more than two levels, the information structure is probably too complex for the bullet points to improve readability.
Pick bullet points instead of numbers/letters when the order does not matter. Pick numbers (for simplicity, prefer Arabic numerals, but Roman numerals can work) or letters when the order does matter (e.g. for steps in a protocol).
Bullet points are useful to break the monotony of reading paragraphs, but when there’s too much point form, the reverse becomes true. Use bulleted lists less than normal prose.