Erratum
Unfortunately, the original version of this article [1] contained an error. The superiority margin difference should be 5 % instead of 10 %. We performed a superiority test of two independent proportions with superiority margin difference of 5 % by PASS 11.0 software again, and the results were the same as mentioned in the paper before. The sentence in the "Sample size calculation" part (Page 5) is corrected as follows:
According to the supposition and as calculated by PASS 11.0 software (NCSS, LLC, Kaysville, Utah, USA), sample size of 239 in each group can achieve 90 % power and to rule out a two-sided type I error of 5 % to detect a superiority margin difference of 5 % in this two-arm trial with equal allocation in each group.
Reference
Wen Z-H, Xuan M-L, Yan Y-H, Li X-Y, Yao D-N, Li G, Guo X-F, Ou A-H, Lu C-J. Chinese medicine combined with calcipotriol betamethasone and calcipotriol ointment for Psoriasis vulgaris (CMCBCOP): study protocol for a randomized controlled trial. Trials. 2014;15:294.
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The online version of the original article can be found under doi:10.1186/1745-6215-15-294.
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Wen, ZH., Xuan, ML., Yan, YH. et al. Erratum to: 'Chinese medicine combined with calcipotriol betamethasone and calcipotriol ointment for Psoriasis vulgaris (CMCBCOP): study protocol for a randomized controlled trial'. Trials 17, 357 (2016). https://doi.org/10.1186/s13063-016-1500-4
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DOI: https://doi.org/10.1186/s13063-016-1500-4