Easthall C, Song F, Bhattacharya D. A metaanalysis of cognitive-based behaviour change techniques as interventions to improve medication adherence. BMJ Open 2013;3:e002749. In the process of preparing this material for inclusion in a doctoral thesis, the following minor errors were noted:

▸ Remien study (tables 1 and 2) – the correct sample size is 215; data were, however, entered correctly.

▸ Van Es study (table 2) – the correct sample sizes for the intervention and control group are 33 and 34 respectively; data were, however, entered correctly.

▸ Pradier and Wagner studies – sample size errors were included in the meta-analysis which means slightly different effect sizes were obtained for these studies as summarised in table 1 below which highlights that the erroneous data have made very minor changes to the effect sizes calculated.

▸ The overall effect size for all studies remains unchanged at 0.34 (0.23 to 0.46).⇓