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Knafl GJ, Knafl KA, Grey M, Dixon J, Deatrick JA, Gallo AM.Knafl GJ, et al. Among authors: deatrick ja.BMC Med Res Methodol. 2017 Mar 21;17(1):45. doi: 10.1186/s12874-017-0296-6.BMC Med Res Methodol. 2017.PMID: 28320340Free PMC article.