An example of the method by which results were presented in the review, showing the effectiveness of alcohol to kill lipid viruses. An overview of the relevant studies included in the review is given and a standard operating procedure iterated from these studies is described. The iterative process is then illustrated by classifying the studies as containing evidence for or against the standard procedure (Table A). Included in this assessment are possible reasons for disagreement between the studies shown ('Possible sources of heterogeneity'). One study in this group did not contain sufficient detail to classify it in these terms and the outcome is listed separately (Table B). The summary table of the evidence includes the standard procedure and comments about the strength of the evidence as well as factors that are identified in the studies as being essential for the desired procedure outcome (critical points).