How to read a paper : getting your bearings (deciding what the paper is about)BMJ 1997; 315 doi: http://dx.doi.org/10.1136/bmj.315.7102.243 (Published 26 July 1997) Cite this as: BMJ 1997;315:243
- Trisha Greenhalgh (firstname.lastname@example.org)a, senior lecturer
- a Unit for Evidence-Based Practice and Policy, Department of Primary Care and Population Sciences, University College London Medical School/Royal Free Hospital School of Medicine, Whittington Hospital, London N19 5NF
The science of “trashing” papers
It usually comes as a surprise to students to learn that some (perhaps most) published articles belong in the bin, and should certainly not be used to inform practice.1 The first box shows some common reasons why papers are rejected by peer reviewed journals.
Why were papers rejected for publication?
The study did not address an important scientific issue
The study was not original (someone else had already done the same or a similar study)
The study did not actually test the authors' hypothesis
A different type of study should have been done
Practical difficulties (in recruiting subjects, for example) led the authors to compromise on the original study protocol
The sample size was too small
The study was uncontrolled or inadequately controlled
The statistical analysis was incorrect or inappropriate
The authors drew unjustified conclusions from their data
There is a significant conflict of interest (one of the authors, or a sponsor, might benefit financially from the publication of the paper and insufficient safeguards were seen to be in place to guard against bias)
The paper is so badly written that it is incomprehensible
Most papers now appearing in medical journals are presented more or less in standard IMRAD format: Introduction (why the authors decided to do this research), Methods (how they did it, and how they analysed their results), Results (what they found), and Discussion (what the results mean). If you are deciding whether a paper is worth reading, you should do so on the design of the methods section and not on the interest of the hypothesis, the nature or potential impact of the results, or the speculation in the discussion.
The assessment of methodological quality (critical appraisal) has been covered in detail in many textbooks on evidence based medicine,2 3 4 5 6 and in Sackett and colleagues' Users' Guides to …