by the authors. For example, good evidence may cease to be of value simply because it is old – trials showing the benefit of treatment may no longer be useful if a disorder changes so that its sensitivity to treatment changes. Similarly, evidence from one part of the world cannot always be applied freely elsewhere.
The evidence may be incomplete. For example, we may know that rates of smoking are increasing among young women but we don't know why.
The evidence may be of poor quality.
If these elements of the Introduction are well presented, then it should be clear what the paper is about and why the authors have chosen to conduct the work that they have. Armed with this background briefing, you can now move on to check the specific objectives of the authors' work (see Chapter 3).
ETHICAL CONSIDERATIONS
Nearly all studies in healthcare that involve contact with people will require ethical approval. What that means is that the researchers will have had to submit their proposals to a panel of experts, such as a local research ethics committee, who decide whether the project is ethical or not. For example, the risks of any research should be outweighed by its benefits and participants should have been given the opportunity to participate or not as they wished, without their decision influencing their medical care.
Most authors will indicate that their study has been approved by the appropriate body governing research ethics – usually either in the Methods section or the Acknowledgements. Increasingly, authors will mention any particular ethical dilemmas raised by their research either in the Introduction or the Discussion of their paper. Where there are particular questions raised by a study, the authors may expand upon them (including, for example, details of the information given to participants and the way in which consent was obtained).
Certain types of research cause particular ethical concerns. For example, young children, or those with cognitive impairment or learning disability, or patients who are unconscious, cannot give consent to participate in research that nonetheless asks extremely important questions about clinical care. In these situations, researchers may undertake research with ethical approval, provided certain criteria are met (see Figure 2.5 from a study of a weight management intervention in adults with a learning disability).
Figure 2.5 Ethical considerations in a study involving adults with a learning disability.
Source: Reproduced from Harris et al. (2017).
CHAPTER 3 The Aims and Objectives
Following the Introduction, you should look for a clear statement of the purposes of the current work. This statement can come in two forms: the aims of the study and the objectives.
Aims are general statements about purpose. For example, the authors might wish to examine the attitudes of hospital nurses to colleagues with mental health problems.
Objectives are specific questions, suggested by previous research or theory. For example, ‘Does taking the oral contraceptive pill increase the risk of stroke among women of childbearing age?' One particular sort of objective is to test an hypothesis.
Because the terminology of hypothesis testing is so widely used, we will start there.
HYPOTHESES
Often, studies will ask more than one question, so they will have several hypotheses. In these circumstances, you should look for a main hypothesis (Figures 3.1 and 3.2) and the other questions will form subsidiary or secondary hypotheses.
Figure 3.1 Statement of a study's main hypothesis.
Source: From Thompson et al. (2000), © 2000 Elsevier.
Figure 3.2 A study with two hypotheses.
Source: From Tebartz van Elst et al. (2000), © 2000 Oxford University Press.
There are important reasons why a study should have only one main question:
If a study tests many hypotheses, then just by chance it is likely to produce positive results for some of them. (See Chapter 31 on hypothesis testing and the possibility of false‐positive results from multiple testing.)
We can trust a negative result only if we know that a study was large enough; otherwise, there is a possibility of false‐negative results. Many researchers therefore make an estimate of sample size to help them decide how big to make their study so that they can avoid this sort of error (see Chapter 13). To do that calculation they need to know what the main outcome of interest is, and the main outcome will be chosen to test the main hypothesis.
There used to be a conventional way of stating a study's hypothesis, which involved the use of a null hypothesis and the description of a study set up to disprove or refute an hypothesis. Although this approach is still sometimes taught, you will almost never come across examples in papers. The null hypothesis was a way of stating a question in the form ‘situation A is no different from situation B'. It arose because certain statistical tests operate by testing whether an assumption of similarity is likely to be true.
The need to refute rather than prove an hypothesis is similarly based on a technical point – about the nature of scientific evidence. In fact, nearly everybody now states their hypotheses in a straightforward way, as an interesting question framed in everyday language. The English doesn't have to be difficult to follow for the science to be right!
OBJECTIVES THAT ARE NOT HYPOTHESIS TESTING
Not all questions are framed as hypotheses, even in quantitative research. For example, in a study examining the rate of antibiotic resistance among post‐operative wound infections the authors might have no definite rate in mind.
And many studies are not designed to test hypotheses at all – for example some are designed to generate new ideas and questions for future research. This is especially true of qualitative research, which is generally speaking more exploratory – asking a question when we might not know what answers to expect and where we don't want to measure something but to understand its nature. In other words, although
