Nature Reviews Rheumatology 12, 486–496 (2016) doi:10.1038/nrrheum.2016.102

In the originally published version of the above Review, in the left-hand panel of Figure 2b the residuals were represented by horizontal rather than vertical double-headed arrows between the individual data points and the regression line, and in the right-hand panel the labels for the axes were inverted; in the legend for Figure 2b and on page 487 of the article where Figure 2 is cited, the description of the two-stage least squares method was inaccurate; and owing to an editorial oversight, a sentence on page 488 mistakenly referred to the occurrence of “reverse causality” instead of “inverse causality”. These errors have been corrected in the online version of the article. Also, in the discussion of the Wald method on page 488, the sentence “However, estimating the effect size of an exposure on the outcome is not possible” has been deleted to avoid ambiguity.