What’s the point of your thesis?
Why are you writing? Well, you want to pass the PhD. You want to be able to put “Dr” on your credit card, and so on.
What do you need to do to succeed? You probably think that you need to write a thesis that convinces the examiner that you’re worthy of the honour. Well that’s true, but there are good ways and bad ways to go about it.
What effect does your writing have on the reader? The way they feel while reading your thesis really matters. If they have to read any sentence three times to work out what you mean, then you’re taking up their time unnecessarily.
Now of course there are some expected standards of formality, but clarity should always come first. Fortunately, there’s an easy way to make your writing clearer.
Shorter sentences are easier to understand (and to write)
If in doubt, make your sentences as short as you can. Flashy writing is optional, clarity is compulsory.
The Flesch Readability Score takes account of the average number of words per sentence, plus other factors such as length of word used, number of words per paragraph, to determine how easy it is to read a piece of text. A low score means it’s harder to read. A negative score is bad news.
For example, comic books score around 90, general plain English between 60 and 70. A university professor will obviously be comfortable with long sentences, with readability scores of 10 or less. But that doesn’t mean that every sentence can be complex.
It’s a good idea to balance long, complex sentences and paragraphs with simpler ones.
Balance: alternate long and short
MS word can give you an average readability score for the whole thesis, but the way you fit long and short sentences together matters more.
Here’s an example from my thesis, with (number of words, readability) after each sentence;
It should perhaps be unsurprising that certain geometric arrangements of matter are preferred by nature (15, 28). Perfect tessellation can only be achieved by triangles, squares and hexagons- of these, the hexagon has the shortest perimeter length per unit area enclosed, and hexagonal packing arrangements are known to be the most efficient (35, 19). Spheres enclose the largest volume per unit surface area, and are intuitively stable forms (14, 47.5). Nature uses the same forms at every length scale; leading to self-similarity and fractal characteristics (15, 30).
The more complex sentence, with 35 words and a readability of 19, is balanced by simpler ones. This brings the average word count per sentence to 19.7 and readability to 34.4. That’s somewhere around the New York Review of Books in terms of readability. Even more complex ideas can be explained the same way;
Figure 1.6 shows the electronic density of states for bulk, 2-D, 1-D and O-D structures (thin films, wires, and nanoparticles) (22, 57.6). The alteration from a continuous to discrete distribution of states arises when the confinement of the structures prevents the formation of a long-range Bloch-type periodic wave potential of the type that is present in an extended crystal (37, 16). The electronic structure approaches the idealized particle in a box potential well (12, 25.4). In the case of quantum dots, the situation may be considered as an intermediate condition between molecular and bulk properties (20, 30).
average (22.7, 34)
Please don’t think you have to measure the readability of every sentence you write! Just be aware that longer sentences make your writing more tiring to read, so you can balance them with shorter ones. It’ll give your writing a natural sense of rhythm.
If you have two very long sentences in succession, try to cut at least one of them. If you can’t, think about making each sentence a whole paragraph. If in doubt, make your sentence shorter.
The first paragraph of any thesis chapter, section or subsection should usually consist entirely of short sentences (around 15 words maximum). This will help ease them in before the technical detail.
Structure: give the reader a break
Sentence length isn’t the only factor in readability. The arrangement of paragraphs, subsections and sections, as well as the visual presentation, has a massive influence. Like sentences, shorter paragraphs are easier to read. If you run over 100 words
Shorter subsections are always easier, giving the reader a regular break. The examiner will probably, at some point, flick through to see how far they have to go. If there’s another 20 pages before the next break, consider putting one in where you can.
Use your judgement
These are only guidelines to use generally. Sometimes a long sentence is needed, or just feels right. Just don’t forget the reader
In case you’re interested, or even if you’re not, the average sentence length in this piece is 14.4 words, with a readability of 56.7