Author: Jon Williamson

EBM+ is interested in using evidence of mechanisms in conjunction with evidence of correlation to help evaluate causal claims in medicine. One objection to this idea is that it is hard to do this in practice.

It’s hard but it’s not impossible …


This was the title of a very nice workshop at Durham on 3rd May, hosted by Julian Reiss. The aim of the work discussed here was to develop, propagate and understand methods for evaluating multifarious evidence.

Monika Schnitzer (Department of Economics, Ludwig-Maximilians-University of Munich) discussed a variety of methods for evaluating public policies, each of which tries to compare what happened after the policy was implemented with what would have happened had the policy not been implemented. Paul Pearce (Defence and Security Analysis Division, Defence Science and Technology Laboratory) explained the structure of a new approach to analysing evidence put in place by the military. He’s a keen advocate of systems thinking. I talked about the principle of total evidence in medicine, including the EBM+ approach. Then Sharon Crasnow (Norco College) talked about mixed methods in the social sciences – a combination of qualitative and quantitative methods – and argued that these support causal pluralism.

A fascinating workshop and a reminder of how difficult it is to amalgamate evidence in practice!

One theory is that physicians gave too much credence to hypothesised mechanisms for which there was little or no evidence. If so, the problem was one of method: too little time spent obtaining solid evidence of mechanisms and too little inclination to properly evaluate the evidence that was available.