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How to Write an Abstract for a Dissertation or Thesis

What is a Thesis or Dissertation Abstract?

The Cambridge English Dictionary defines an abstract in academic writing as being “a few sentences that give the main ideas in an article or a scientific paper” and the Collins English Dictionary says “an abstract of an article, document, or speech is a short piece of writing that gives the main points of it”.

Whether you’re writing up your Master’s dissertation or PhD thesis, the abstract will be a key element of this document that you’ll want to make sure you give proper attention to.

What is the Purpose of an Abstract?

The aim of a thesis abstract is to give the reader a broad overview of what your research project was about and what you found that was novel, before he or she decides to read the entire thesis. The reality here though is that very few people will read the entire thesis, and not because they’re necessarily disinterested but because practically it’s too large a document for most people to have the time to read. The exception to this is your PhD examiner, however know that even they may not read the entire length of the document.

Some people may still skip to and read specific sections throughout your thesis such as the methodology, but the fact is that the abstract will be all that most read and will therefore be the section they base their opinions about your research on. In short, make sure you write a good, well-structured abstract.

How Long Should an Abstract Be?

If you’re a PhD student, having written your 100,000-word thesis, the abstract will be the 300 word summary included at the start of the thesis that succinctly explains the motivation for your study (i.e. why this research was needed), the main work you did (i.e. the focus of each chapter), what you found (the results) and concluding with how your research study contributed to new knowledge within your field.

Woodrow Wilson, the 28th President of the United States of America, once famously said:

“If I am to speak ten minutes, I need a week for preparation; if fifteen minutes, three days; if half an hour, two days; if an hour, I am ready now.”

The point here is that it’s easier to talk open-endedly about a subject that you know a lot about than it is to condense the key points into a 10-minute speech; the same applies for an abstract. Three hundred words is not a lot of words which makes it even more difficult to condense three (or more) years of research into a coherent, interesting story.

What Makes a Good PhD Thesis Abstract?

Whilst the abstract is one of the first sections in your PhD thesis, practically it’s probably the last aspect that you’ll ending up writing before sending the document to print. The reason being that you can’t write a summary about what you did, what you found and what it means until you’ve done the work.

A good abstract is one that can clearly explain to the reader in 300 words:

  • What your research field actually is,
  • What the gap in knowledge was in your field,
  • The overarching aim and objectives of your PhD in response to these gaps,
  • What methods you employed to achieve these,
  • You key results and findings,
  • How your work has added to further knowledge in your field of study.

Another way to think of this structure is:

  1. Introduction,
  2. Aims and objectives,
  3. Methods,
  4. Results,
  5. Discussion,
  6. Conclusion.

Following this ‘formulaic’ approach to writing the abstract should hopefully make it a little easier to write but you can already see here that there’s a lot of information to convey in a very limited number of words.

How Do You Write a Good PhD Thesis Abstract?

The biggest challenge you’ll have is getting all the 6 points mentioned above across in your abstract within the limit of 300 words. Your particular university may give some leeway in going a few words over this but it’s good practice to keep within this; the art of succinctly getting your information across is an important skill for a researcher to have and one that you’ll be called on to use regularly as you write papers for peer review.

Keep It Concise

Every word in the abstract is important so make sure you focus on only the key elements of your research and the main outcomes and significance of your project that you want the reader to know about. You may have come across incidental findings during your research which could be interesting to discuss but this should not happen in the abstract as you simply don’t have enough words. Furthermore, make sure everything you talk about in your thesis is actually described in the main thesis.

Make a Unique Point Each Sentence

Keep the sentences short and to the point. Each sentence should give the reader new, useful information about your research so there’s no need to write out your project title again. Give yourself one or two sentences to introduce your subject area and set the context for your project. Then another sentence or two to explain the gap in the knowledge; there’s no need or expectation for you to include references in the abstract.

Explain Your Research

Some people prefer to write their overarching aim whilst others set out their research questions as they correspond to the structure of their thesis chapters; the approach you use is up to you, as long as the reader can understand what your dissertation or thesis had set out to achieve. Knowing this will help the reader better understand if your results help to answer the research questions or if further work is needed.

Keep It Factual

Keep the content of the abstract factual; that is to say that you should avoid bringing too much or any opinion into it, which inevitably can make the writing seem vague in the points you’re trying to get across and even lacking in structure.

Write, Edit and Then Rewrite

Spend suitable time editing your text, and if necessary, completely re-writing it. Show the abstract to others and ask them to explain what they understand about your research – are they able to explain back to you each of the 6 structure points, including why your project was needed, the research questions and results, and the impact it had on your research field? It’s important that you’re able to convey what new knowledge you contributed to your field but be mindful when writing your abstract that you don’t inadvertently overstate the conclusions, impact and significance of your work.

Thesis and Dissertation Abstract Examples

Perhaps the best way to understand how to write a thesis abstract is to look at examples of what makes a good and bad abstract.

Example of A Bad Abstract

Let’s start with an example of a bad thesis abstract:

In this project on “The Analysis of the Structural Integrity of 3D Printed Polymers for use in Aircraft”, my research looked at how 3D printing of materials can help the aviation industry in the manufacture of planes. Plane parts can be made at a lower cost using 3D printing and made lighter than traditional components. This project investigated the structural integrity of EBM manufactured components, which could revolutionise the aviation industry.

What Makes This a Bad Abstract

Hopefully you’ll have spotted some of the reasons this would be considered a poor abstract, not least because the author used up valuable words by repeating the lengthy title of the project in the abstract.

Working through our checklist of the 6 key points you want to convey to the reader:

  1. There has been an attempt to introduce the research area, albeit half-way through the abstract but it’s not clear if this is a materials science project about 3D printing or is it about aircraft design.
  2. There’s no explanation about where the gap in the knowledge is that this project attempted to address.
  3. We can see that this project was focussed on the topic of structural integrity of materials in aircraft but the actual research aims or objectives haven’t been defined.
  4. There’s no mention at all of what the author actually did to investigate structural integrity. For example was this an experimental study involving real aircraft, or something in the lab, computer simulations etc.
  5. The author also doesn’t tell us a single result of his research, let alone the key findings!
  6. There’s a bold claim in the last sentence of the abstract that this project could revolutionise the aviation industry, and this may well be the case, but based on the abstract alone there is no evidence to support this as it’s not even clear what the author did.

This is an extreme example but is a good way to illustrate just how unhelpful a poorly written abstract can be. At only 71 words long, it definitely hasn’t maximised the amount of information that could be presented and the what they have presented has lacked clarity and structure.

A final point to note is the use of the EBM acronym, which stands for Electron Beam Melting in the context of 3D printing; this is a niche acronym for the author to assume that the reader would know the meaning of. It’s best to avoid acronyms in your abstract all together even if it’s something that you might expect most people to know about, unless you specifically define the meaning first.

Example of A Good Abstract

Having seen an example of a bad thesis abstract, now lets look at an example of a good PhD thesis abstract written about the same (fictional) project:

Additive manufacturing (AM) of titanium alloys has the potential to enable cheaper and lighter components to be produced with customised designs for use in aircraft engines. Whilst the proof-of-concept of these have been promising, the structural integrity of AM engine parts in response to full thrust and temperature variations is not clear.

The primary aim of this project was to determine the fracture modes and mechanisms of AM components designed for use in Boeing 747 engines. To achieve this an explicit finite element (FE) model was developed to simulate the environment and parameters that the engine is exposed to during flight. The FE model was validated using experimental data replicating the environmental parameters in a laboratory setting using ten AM engine components provided by the industry sponsor. The validated FE model was then used to investigate the extent of crack initiation and propagation as the environment parameters were adjusted.

This project was the first to investigate fracture patterns in AM titanium components used in aircraft engines; the key finding was that the presence of cavities within the structures due to errors in the printing process, significantly increased the risk of fracture. Secondly, the simulations showed that cracks formed within AM parts were more likely to worsen and lead to component failure at subzero temperatures when compared to conventionally manufactured parts. This has demonstrated an important safety concern which needs to be addressed before AM parts can be used in commercial aircraft.

What Makes This a Good Abstract

Having read this ‘good abstract’ you should have a much better understand about what the subject area is about, where the gap in the knowledge was, the aim of the project, the methods that were used, key results and finally the significance of these results. To break these points down further, from this good abstract we now know that:

  1. The research area is around additive manufacturing (i.e. 3D printing) of materials for use in aircraft.
  2. The gap in knowledge was how these materials will behave structural when used in aircraft engines.
  3. The aim was specifically to investigate how the components can fracture.
  4. The methods used to investigate this were a combination of computational and lab based experimental modelling.
  5. The key findings were the increased risk of fracture of these components due to the way they are manufactured.
  6. The significance of these findings were that it showed a potential risk of component failure that could comprise the safety of passengers and crew on the aircraft.

The abstract text has a much clearer flow through these different points in how it’s written and has made much better use of the available word count. Acronyms have even been used twice in this good abstract but they were clearly defined the first time they were introduced in the text so that there was no confusion about their meaning.

Conclusion

The abstract you write for your dissertation or thesis should succinctly explain to the reader why the work of your research was needed, what you did, what you found and what it means. Most people that come across your thesis, including any future employers, are likely to read only your abstract. Even just for this reason alone, it’s so important that you write the best abstract you can; this will not only convey your research effectively but also put you in the best light possible as a researcher.

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