Studies attempting the quantify the economic effects for the UK of Brexit have come up with conflicting results – ranging from significant advantages to marked losses. Using a meta-analysis, this column shows this can be explained by different methods and assumptions, as well as varying coverage of effects. The forward-looking, model-based studies are unable to capture many positive effects of economic integration on welfare and growth. In comparison, backward-looking studies tend to find significantly larger trade effects of economic integration agreements. The meta-analysis suggests that in case of Brexit, GDP losses for the UK in the range of 10% or more cannot be ruled out in the long run.