This article refers to:
Ronnie Pingel and Ingeborg Waernbaum (2014) Effects of correlated covariates on the asymptotic efficiency of matching and inverse probability weighting estimators for causal inference. Statistics, http://dx.doi.org/10.1080/02331888.2014.925899
When the above article was first published online, the fraction 1/2 appeared at incorrect positions of several exponents. This has now been corrected in both the print and online versions.
Taylor & Francis apologises for this error.