Frequently, having formulated a three part question, searched and read the literature, we find that the evidence does not answer our original question well. Describing what was found and how close it came to answering our question is usually left to the authors who may tabulate the results (such as those presented by the BETs from Manchester Royal Infirmary). An alternative is to present the results in a graphic form and this maybe thought of as complementary to the tabulated method in much the same way as forest plots have been used to present the data of meta-analyses.

The method consists of constructing four axes (fig 1). The first three relate to the question. Specifically the patient population, the intervention (and its …