Draft the sentence that states the study's aim
The sentence that states a study's aim says what the study set out to find out. It describes the knowledge to be produced rather than the actions taken, carries the PICOT items where they are relevant, and frames the question so that it leads into what was done. Where a journal sets abstract subheadings with complete sentences beneath them, it opens with the journal's own term.
The knowledge to be produced
The research question can be called the purpose statement, because a study's purpose is more often expressed through aims and hypotheses than through research questions. Stating the research question clearly in the introduction is vital to tell the reader what the study is about, and one focused question is usually better than many. The question may be stated as a query or as a hypothesis but is often phrased as a statement of intent, as in we examined residential exposure to aircraft noise and mortality from myocardial infarction, taking air pollution into account. One guide would rather see the question framed as a direct query or even as a hypothesis, as in the clearly stated our goal was to determine whether the in-hospital rate of death among patients requiring transfusion was lower among those who received blood after short-term storage than among those who received blood after long-term storage. Many authors state the research question less explicitly, and that guide's author has learned to be content with such somewhat vague statements, as in the purpose of this study was to investigate both early and late dumping syndromes after gastrectomy for gastric cancer in 2 high-volume centers in Japan, though at that point in the paper they leave that author still unaware of the question the study set out to answer.
The purpose statement should describe the knowledge to be produced, not the actions involved, because the purpose of research is not to do experiments or evaluate patients but to find something out by doing them. Every research project involves studying, assessing, evaluating or investigating something, so the purpose should not be written as doing one of those things.
The PICOT items
The PICOT approach recommends that the purpose statement specify, where relevant, the target population or problem, the intervention of interest, the comparator, the key outcomes, and the time frame over which the outcomes are assessed, with the T sometimes standing instead for the type of study design.
In the research question is implantation of a multifocal-intraocular-lens in presbyopia patients with cataract or having refractive lens exchange effective to correct presbyopia?, the population is presbyopia patients with cataract and the outcome is corrected presbyopia, but nothing is said about the time frame and the intervention cannot be told apart from the comparator. One editor would ask the writer about such a question, assuming that one of the interventions is of more interest than the other and that it should be possible to tell them apart. The description of the patients sits in the middle of the sentence and is written in a nonparallel way, so it seems to refer only to those who had the implant (a misplaced modifier); placed at the start of the sentence, it refers more clearly to both procedures. If both interventions are of equal interest, one revision is in patients with presbyopia and cataract, can presbyopia be effectively corrected by a multifocal-intraocular-lens implant or by a refractive lens exchange?; if the implant is of more interest than the lens exchange, another is in patients with presbyopia and cataract, does a multifocal-intraocular-lens implant correct presbyopia more effectively than a refractive lens exchange? Neither revision keeps the word implantation, a verb turned into a noun (a nominalisation).
The question and the approach
The study question is the most fundamental part of a research manuscript. It engages readers by sparking their curiosity and guides them into the next part of the research story. Many medical writers craft a study question that fails at one or both of these tasks, which weakens the story, but a formula ensures that a persuasive question accomplishes both. In the STACR story structure (setup, tension, action, climax, resolution), the study question is the tension that sparks the reader's curiosity and motivation to keep reading.
A good tension states the gap the study aims to fill by framing a question, then lays out the approach to answering it; in short, it follows the formula to learn X, we did Y, as in to determine the effectiveness of methotrexate in treating chronic kidney disease, we examined serious adverse events in adults with chronic kidney disease who were treated with high and low doses of methotrexate. The formula is not always so clear-cut and can be woven over several sentences, as in a study that set out to develop a diagnostic scoring system for extubation readiness in patients undergoing neurosurgery, surveyed physicians on what led them to delay extubation, and then developed the system and evaluated how well it predicted extubation success.
Pitfalls in framing the question
Five common pitfalls weaken the study question, and with it the research story.
Stating only the objective, with phrases such as we aimed to or we sought to, sparks curiosity but gives the reader no bridge from the question into what was done, so the sentence should also say what was done.
Stating only the approach, with phrases such as we measured or we assessed, guides the reader in but assumes they already know the question and, by sparking no curiosity, drains the question of persuasion, so the sentence should also say what was to be learned.
Reversing the order to we did Y to learn X states the approach before the question, an order that does not follow a logical flow and can make more work for the reader or even confuse them. For example, in this study, we analyzed data from an ongoing cohort study of women of reproductive age to examine the potential association between adverse pregnancy outcomes and energy drink intake during pregnancy is better written as to examine the potential association between adverse pregnancy outcomes and energy drink intake during pregnancy, we analyzed data from an ongoing cohort study of women of reproductive age.
Stating only the hypothesis turns the question into a prediction that lacks persuasion, even though hypotheses are an important part of the scientific method and many fields believe a hypothesis must be stated for the work to count as research. The question should be stated with the formula, and the hypothesis can then follow it.
Summarising the key findings, or even the conclusions, straight after the question gives the story away and satisfies the reader's curiosity instead of enticing them to keep reading, though some writers believe the summary is a conventional standard. The findings should instead be kept for the climax in the discussion.
The conclusion and the abstract
A well-written purpose statement eases the writing of the conclusion.
Where a journal requires the abstract to have subheadings such as Objective, Goal, Aim or Purpose, and complete sentences beneath them, the sentence should open with the journal's own term, because people have different ideas about what these words mean and whether they differ. If the subheading is objective, the sentence should not begin our aim was, or worse the study's aim was; the study itself should not be the subject of the sentence.