Many writers follow the unhelpful writing ‘rule’ that “…you should never repeat yourself”. Unfortunately, this causes writers to keep using different words for the same thing, which can cause confusion, or to only state findings once, which can easily be overlooked by busy readers. In this blogpost, I will discuss when repetition is crucial in science writing by making a distinction between Necessary Repetition and Unnecessary Repetition.

Necessary repetition
Repetition is important for emphasising or reinforcing a key message or point. Research has shown that repeating information can influence people’s belief that information is true. While this concept is good news for factual writing, unfortunately, it might be partially responsible for the effectiveness of misinformation in social media.

 
Repetition can be important tool in research writing in three key ways:

 
1. Connecting ideas between sentences and sections
Repeating the grammatical subject (or key sentence topic) is an important tool in connecting sentence ideas throughout a paragraph or section.

 
An example is from the abstract of this paper: ‘Crop cover and nutrient levels mediate the effects of land management type on aquatic invertebrate richness in prairie potholes’, where the key research subject ‘aquatic invertebrates’ is repeated 5 times.

 
2. Creating rhythm and predictability
Repetition can set up an expectation of when and where the information will be repeated. For example, if you wanted to discuss results, some of which were increasing in magnitude, while some where decreasing, you might first repeatedly refer to what was increasing, then repeatedly refer to what was decreasing.

 
While repetition can be used to emphasise an important point, ensure you don’t choose too many points to repeat as this reduces the power of emphasis.

3. Information recall
You need to write for the tired or busy reader: don’t assume the reader will thoroughly read every page of your document to find out how and why you did your study. The most important place to summarise the key aim, method, hypotheses and findings are in the abstract of a paper or in the executive summary of a report.

Presenting the findings in the results, repeating them in the discussion, then summarising them in abstract, builds your logical sequence of evidence that supports your analysis and key findings. For example, results might be first presented in a figure or table, then summarised in the text description of the results, then again restated in the discussion and summarised in the abstract. Additionally, the key findings can be presented in the title.

When repetition is unnecessary or confusing
Repetition is unnecessary if information is restated using different words that just add to the word count without creating clarity or emphasis.

 
1. Tautology
An example of unnecessary repetition is tautology which is repeating an idea, statement, or word using different words or phrases.
Some examples:
‘…customised electronic data deliverables specific to client requirements’.
‘The aim of achieving the ultimate goal’.
‘…approaches were classified into two classes: specific hardware design and algorithm optimisation’.
‘…an accelerated test which can accurately determine differences in tool life with a high level of confidence was developed.’
‘… is dominated by three main types’.
‘This needs to be paraphrased in your own words.

2. Interchanging terminology: switching from one term to another to describe the same thing
If a key term (e.g. aquatic invertebrates) or factor is described throughout a document interchangeably using different terms, this can greatly confuse the reader as they may think you are actually discussing different objects, organisms or things. I refer to this as ‘interchanging terminology’. Don’t assume your audience is so familiar with your topic that you can easily switch between one term and another.

 
Using the previous example, avoid referring to ‘aquatic invertebrates’, as ‘aquatic organisms’, ‘invertebrates’, or ‘insects’ as these are three different grouping of organisms. If your topic was ‘aquatic invertebrates’, referring to them as ‘aquatic organisms’ would incorrectly include vertebrates (e.g. fish), referring to them as ‘invertebrates’ would incorrectly include non-aquatic invertebrates (e.g. ants and millipedes), and referring to them as ‘insects’ would incorrectly exclude non-insect aquatic invertebrates (e.g. molluscs and crustaceans). Just use ‘aquatic invertebrates’ throughout, even if you think it is boring.

 
A common example of interchanging terminology in methods sections of reports and papers is the use of ‘site’, ‘area’ and ‘location’ to describe the same thing. A reader might wonder if the ‘site’ and the ‘area’ were in fact different places or if the ‘site’ was part of the ‘area’ or if the ‘area’ was part of the ‘location’.

3. Self-plagiarising
Self-plagiarising is when you repeat exact sentences from different parts of your document. This is usually unnecessary unless you need to quote yourself, criteria or other information (e.g. deliverables or legislation). Each sentence that you write has a unique function depending on where it is used in a paragraph or section. If you are repeating your findings in different parts of your paper (as per the Necessary Repetition example above), you still need to paraphrase your repetition to reflect it’s different location and nuanced meaning.

4. Overuse of nominalisations in a sentence
Nominalisation is the grammatical process of turning verbs or adjectives into nouns or noun phrases.

For example:
‘We conducted an evaluation of the event’.

 
This sentence has two descriptions of action ‘we conducted’ and ‘evaluation’. However, the key action in this sentence is ‘evaluation’, which is a noun. This forces unnecessary repetition as every sentence always needs a verb or verb phrase (‘we conducted’). This sentence can be more concise by turning ‘evaluation’ back to ‘evaluate’ and removing ‘we conducted’ to ‘We evaluated the event.’ or ‘The event was evaluated’.