Therapy: Critical Appraisal Part 2 (Interpreting Results)
This chapter deals with the second part of the critical appraisal. We want to know: ‘How good is the treatment?’ We would love to have one sentence with one figure to answer this question, but in life, one figure is not enough to tell the whole story about many things. For example, we ask our children: How good are your marks? If he says 99 %, we feel happy. But then soon we want to know, is it the best in the class – in other words, what is his/her position relative to the other students. How many students have marks below this? How many have marks above this? This is to know his relative position. This is described in terms of percentile. The per cent of marks in absolute terms is 99, but it is possible that most students had it (the exam was very easy). Some testing services use per cent, percentile, grade (A1, A2, B1, etc.) and GPA (grade point average) to describe the results. Each figure may give a different perspective and may appeal to different constituencies. This is why stock markets always use at least two figures to describe what happened on the day: usually one to describe the difference in actual figures (absolute difference) and one to describe it in per cent terms (relative to the opening figure).