The curious thing about an abstract is that although, after the title, it is the first text to be read, it is usually the last thing to be written in the dissertation. The reason is quite simple. Writing an abstract is a highly developed skill. On one page, or less, the author needs to summarise the entire body of the research work, describing the research question(s), the methods used to gather new evidence, how this evidence was analysed, list the key findings, and say why these are important. This is a tall task, demanding a number of difficult decisions about what to include and what to leave out of the text. The added pressure is that this might be the one and only part of your research that a browsing researcher of the future will read, so you need to captivate their interest in half a page or so. On websites such as https://ethos.bl.uk/ which is the British Library catalogue the entire output of completed UK PhDs, are the abstracts that researchers consult to decide whether to read the whole PhD dissertation, or not. This is a good site to consult to gain an idea of what is needed, but creating your own takes practice.
For this reason, a good supervisor will encourage the research student to finesse their skill at abstract writing by trying several versions before the culminating attempt. It is sometimes said that to ask a research student what their PhD is about at the beginning of their studies is to get a verbal paragraph in response, but to ask the same question at the end gets a succinct response of 5 or 6 words. This is because over the intervening period, the researcher has honed their analytical skills and (hopefully) their ability to separate what is really important, from that which is interesting but incidental to the main research question. The abstract is about what the reader needs to know, rather than the wider perspective on what might be nice to know.
Writing a concise abstract is a skill that will also serve an author well if/when they progress to submitting a paper to an academic journal. Again, the objective is to capture the essence of the article and grab the attention of the prospective reader. In a society awash with information, it is the ability of information to attract our attention that will distinguish it from the things that do not get noticed, and do not get passed on. In ‘the attention economy’ getting noticed is perhaps even more important that the information itself. If no-one ever reads your brilliant idea, it slowly moves to the graveyard of good ideas. There is a careful balance to be achieved between sensationalist headlines and dry-as-dust reporting, and though the title needs to reflect this, the real meat of what the text is about is contained in a cleverly worded abstract. Ask yourself, what does this abstract actually tell us? For this reason, it is almost never too early for a research student to begin studying the structure of a useful abstract. According to Polonius (in Hamlet) ‘brevity is the soul of wit’ and it is also a very powerful academic skill.