Effective Listing

Lists are a potent tool in business and technical writing. They save time by delivering at-a-glance content. They add interest by breaking up monolithic stretches of plain text. They add clarity through juxtaposition of like items. With lists you can communicate quickly and succinctly, but only when you know the rules to effectively wield them. 

Bullets or Numbers?

Confusion over when to use bullets versus numbers is common in my work as a computer-book editor. Authors frequently make the opposite choices from what they should make. You'd be surprised at how often I see bullets used to denote a sequence of steps in a process. 

Bullet lists denote sets. Following is an ordinary bullet list showing the parts in a typical bicycle that provide motive power from your legs to the rear wheel:

  • Bottom-bracket
  • Cassette
  • Chain
  • Crankset
  • Freehub
  • Pedals

The set of parts involved is the same no matter the order in which you list them. Use of a bullet list is appropriate.

Now change the intent of the list. Instead of conveying the set of parts involved, change the intent to convey the path of the pedaling force as it moves from your legs to the rear wheel. When you pedal a typical bicycle, your motive force is transmitted in order over over the following parts:

  1. Pedals
  2. Crankset
  3. Bottom-bracket
  4. Chain
  5. Cassette
  6. Freehub

Numbers are the correct choice in this example. They convey a sense of sequence, and that sequence is precisely the message the list is intended to convey.

Choose between bullets and numbers by thinking about whether you are conveying steps in a process or a set of items. Apply the following heuristic to make the correct choice:

  • Choose numbers to convey a series of actions
  • Otherwise, choose bullets

Make bullets your default choice. Numbers are best when presenting an order, such as steps in a process for the reader to follow. Choose numbers only when you have a specific reason, and that reason should somehow be wrapped up in conveying a sequence or a process.

Note. Everything I've said is a matter of convention, or style. No stone tablets are involved. In academic writing it is actually common to use numbered lists all the time, and sometimes lettered lists too. Know your publisher. Know your audience. Know their expectations, and deliver on those. 

Terms and Definitions

Term/definition lists are the right choice when your list items follow the pattern of presenting a term or a concept followed by a definition or an exposition. Following is an example describing some of the bicycle parts mentioned earlier:

Bottom-bracket
Holds the crankset securely in the frame, allowing the crank arms to spin in a circle and transmit force through the chainrings and into the chain.
Cassette
Is an assembly of sprockets that fits onto the rear bicycle wheel to receive the motive force as transmitted by the chain.
Chain
Connects the chainrings to the rear cassette in order to transfer force from the chainrings to the cassette.

Terms are often run in to their descriptions, especially when the terms are short. When that's done, the terms are often made boldface as in the following example:

  • Crankset. Converts your mostly downward pedaling forces into a rotary motion.
  • Freehub. Provides the interface between the cassette and the rear wheel.
  • Pedals. Transfer force from the soles of your feet to the crank arms.

    Avoid bullets when using this format of running the term into the description. Quite often I see authors creating essentially a mashup combining the bullet and the term/definition style. Here's an example of what not to do:

    • Crankset. Converts your mostly downward pedaling forces into a rotary motion.
    • Freehub. Provides the interface between the cassette and the rear wheel.
    • Pedals. Transfer force from the soles of your feet to the crank arms.

    The bullets are redundant and should not be used. The boldface terms are enough to demarcate the list items, and the bullets merely add clutter. Making bold or otherwise setting off the terms is all you need.

    Note. My own publisher, Apress, most often uses the run-in style of term/definition list. The style Unnumbered List in the Apress Word template is the one to use. It creates a list having no bullets or numbers, and then you can boldface the terms.

    You can apply the term/definition style of list to anything fitting the general pattern of a short term or phrase followed by a longer definition or exposition. Following is an example describing implementation alternatives for bicycle parts:

    • The bottom-bracket attaches the crankset to the frame. Numerous styles exist. The so-called, square-taper design was almost universal back in the day, but has been superceded by Octalink, ISIS, and various external-bearing designs. Press fit designs are now gaining ground, in which the shells press into the frame in much the same way as do headset cups.
    • The cassette is an assembly of sprockets transferring force from the chain to rear wheel. The cassette design came into popularity at about the time eight-speed drivetrains were introduced. Cassettes are now available in eight-speed, nine-speed, ten-speed, and even in some eleven-speed configurations.
    • The chain transfers force from the crankset to the cassette. Chains are like cassettes in that they come sized for different numbers of sprokets. Chain widths are sized for eight-, nine-, ten-, and eleven-speed cassettes. Take care when replacing a chain to buy the correct width for the gearing on your bike.

    Remember not to decorate term/definition lists with bullets, nor with numbers. Keep your lists simple, and don't mix the attributes of the different list types.

    Parallelism and Balance

    Parallelism and balance bring unity to a list by making all items similar in form, in structure, in length, and of the same type. Parallelism covers the similarity of the items. Balance refers to the length of list items and the depth of detail provided.

    Imagine an airline pilot performing a a preflight inspection of a commercial jet-liner. What might that pilot look for? Following is a list of possible problems the pilot might look for. The list is good example of poor parallelism.

    • Fuel leaks
    • Hydraulic leaks
    • Tire damage
    • Bird strike damage
    • Empty ball-point pen

    See that last item? It's not parallel in type with the others. The pilot may really care that he's got a working ink pen, but that item is not in the same class as the others in the list. The ink pen can be mentioned in a different list, possibly of cockpit items, or of pilot personal items, or it can be mentioned in a body text paragraph, but it does not belong in a list of problems to check for on the plane itself.

    Tip. Programmers can think of a list as a class in the sense of object-oriented programming. Each item in a list then must be an instance of the class. The class definition in the preceding list can be thought of as: "Possible problems with the airplane". From that perspective, the ball-point pen clearly is not of the correct type for that particular list.

    Following is another example of parallelism error. This time it involves grammar as well as type. This list mentions several things that a paramedic might want to check during a patient examination:

    1. Skin color and dryness
    2. Respiration
    3. Put the patient on the cot
    4. Pulse
    5. Blood-pressure
    6. Ask about symptoms

    You can see that items #3 and #6 do not fit the pattern. The grammar is off. All the other items are nouns, whereas #3 and #6 are imperative sentences.

    Item #6 can be rewritten as "Symptoms" to appear parallel in form with the other items. However, symptoms in emergency medicine are technically not something one checks, but rather are something one must ask the patient to describe. Rewriting #6 is an expediency to improve the form of the list while leaving a subtle parallelism error that few readers will notice. 

    Item #3 doesn't belong in the list it all. It can't easily be rewritten as a noun without being nonsensical. One could say "Cot", but it hardly makes sense for a medic to check the cot when the medic is examining the patient, at least not in the sense of making a diagnosis. One could rewrite all six items as imperative statements, and then the list introduction must be revisited.

    You have your work cut out for you when confronted with a case of parallelism gone awry like in the patient exam list. Step back and think about what you are trying to accomplish, about what you truly wish to communicate. You may need to rewrite your introduction to the list, write an entirely different list, or completely reorganize and rewrite the immediate content and surrounding paragraphs. 

    Balance refers to the length of list items and the amount of detail provided. Don't allow items to become drastically dissimilar in length. Let's revisit the term/definition list describing the various parts in a bicycle drivetrain. Here is that list again, but with a greatly expanded entry for the cassette:

    Bottom-bracket
    Holds the crankset securely in the frame, allowing the crank arms to spin in a circle and transmit force through the chainrings and into the chain.
    Cassette
    Is an assembly of sprockets that fits onto the rear bicycle wheel to receive the motive force as transmitted by the chain. The individual gears, what most people consider as gears, are properly termed sprockets. Low-end bikes and many older bikes come with freewheels rather than cassettes. The freewheel design is an older design that would thread onto the right side of a bicycle hub. A freewheel contains the mechanism that would allow a bike to coast, and it holds the sprockets providing different gear ratios.
    Freewheel hubs began to suffer problems as the number of sprockets increased past seven. You see, the freewheel hub has a narrower bearing spacing, and the right side of the axle was cantilevered out well past the width of the hub. As freewheels became wider, so did the amount of cantilever, and the increased leverage made it easier for the axle to be bent and damaged in response to going over a bump or down a curb. Manufacturers switched to the modern, freehub design to solve that problem. This newer design elimininates excessive cantilever while making it much easier to replace worn cassettes with fresh, new ones.
    Chain
    Connects the chainrings to the rear cassette in order to transfer force from from the chainrings to the cassette.

    Clearly I've gone way over the top, and my entry on cassette has became a case of tl;dr – too long; didn't read; The entry is way out of balance with the others. It provides too much detail. One solution is to increase the detail of the other entries so that they are all more or less equally as long. The better approach in this case is to shorten the entry for cassette, and either delete the extra detail or move it to some other part of the book or article that is being written. I won't lie to you. Sometimes it takes some work and some thought and some rewriting to get to a solution that delivers the content you wish to deliver while avoiding problems in balance and parallelim.

    Introductions and Coherence

    Good introductions bring coherence to your writing. Never let a reader encounter a list without introducing the list for what it is. Write specific introductions like those seen in this article. For example, here is a list of items to pick up on my next grocery shopping trip:

    • Coca-Cola Vanilla
    • Spearmint Altoids
    • Better Made Potato Chips
    • Buy some beer

    The goal is to make each item fit the introduction. I've introduced this list as one of items to pick up. I should be able to say the words "I'll pick up" followed by each item name. Let's test that:

    • I'll pick up Coca-Cola Vanilla
    • I'll pick up Spearmint Altoids
    • I'll pick up Better Made Potato Chips
    • I'll pick up Buy some beer

    The list fails. The fourth item breaks parallelism, and breaks the introduction too. The beer needs to be thrown out. The other three items are good; I'll buy those.

    •  Tip. Don't overlook the transition between a list and the body text paragraph that follows it. Make sure the transition from list back to body text is smooth and easy to follow. I like to avoid having a section of text end with a list, and often rework my text to include at least one body text paragraph following a list.

    Simplicity and Brevity

    Aim for simplicity in your lists. Keep items short and to-the-point. One reason for using a list in the first place is to help readers scan and comprehend your message faster than if they had to read it in paragraph form. Don't ruin the effect by writing long and overly complicated list items.

    Sometimes it's tempting to write nested lists. I don't like to go down that path unless the number of nested list items is low. I also don't like to have a wide mismatch between the number of nested items under each parent item. If one parent item has ten children, and another parent list item has but two children, then I'm going to be stepping back and thinking about other approaches I might take. I also don't like to nest more deeply  than two levels. More than just a parent-child list indicates to me a loss of control over my content. Readers aren't going to easily follow a deeply-nested list structure, and I will rewrite to simplify my presentation.

    Rethinking and Rewriting

    Writing is hard work. It really is. It's easy to go down the happy path and illustrate good practices for writing effective lists. It's not always so easy to correct a deviation from those practices. Sometimes it's downright hard. An error in parallelism might indicate just a simple rewrite of a list item. Other times it can indicate a restructuring of your document, the addition of new sections or subsections, and quite a bit of unexpected writing and rewriting. Do the work! Don't despair. Do the work. Polish your text. The results are worth it.