How to Read a paper

Editor's Notes

1. RCTs not so good for measuring prognosis or a diagnostic tool – a cohort study is better for this.
2. The way a random number table works is as follows: A printed sheet is provided with a string of random numbers between 1 and 1000 (or whatever). As each person arrives the investigator looks at the next number in the list: if it is even the participant is assigned to the control group; if it is odd they are assigned to the intervention group (or vice versa). The number is then crossed out and the next participant gets the next number.
3. What could possibly happen to make atypical the sample that was obtained? Was the group from which the sample was drawn unusual in any way? Could the method of drawing the sample have introduced bias? Could certain types of participant have been selectively lost ? If the sample is “100 subjects recruited at random from patients with psychotic symptoms admitted to Promenade Ward” then the population is “All possible patients with psychotic symptoms admitted to Promenade Ward” NOT “all possible patients in Mill View” The paper would have to make the case about why there was no important difference between patients in Promenade Ward, and patients in Mill View. Day-time television phone-in polls are self selecting
4. Examples include A nurse who has a personal preference for Treatment A unconsciously scoring patients on Treatment A more favourably than those on Treatment B. What is the solution? ‘Blinding’. Can be single/double/triple blinded. A patient knows that they are being observed and acts differently / A patient knows that they are undergoing a new treatment and acts differently (Only one of these can ethically be avoided!)
5. It’s important to be clear about the distinction between the outcome value in the sample studied (x), and the outcome value in the population (y). It is impossible to find out the value of y without studying every single member of the population, so we find x instead. But, it is highly unlikely that x will be exactly equal to y because of natural variations in the population. What we want to know is: how close to y is x?
6. Steer a careful path between the bland gullibility of believing everything and the strenuous intellectualism of formal critical appraisal. BECAUSE for instance:- 1% rule: it’s said that only 1% of published evidence is rigorous enough to change practice. Article are sent to journals for various reasons by various people. For instance Doctors are required to publish x number of articles – many articles state in no uncertain terms that the evidence isn’t strong and usually they conclude that more research is required. So on the bases of these article you wouldn’t have a lot of confidence in changing your practice Determining the strengths and weaknesses of research design, i.e. the introduction of bias in study design Examining the adequacy of the authors interpretation of the findings: does what they conclude match the results that they report.