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Hatch R, Young D, Barber V, Harrison DA, Watkinson P.Hatch R, et al.BMC Med Res Methodol. 2017 Mar 27;17(1):49. doi: 10.1186/s12874-017-0319-3.BMC Med Res Methodol. 2017.PMID: 28347296Free PMC article.Clinical Trial.