REMEDIUMREMEDIUM1561-59362658-3534Joint-Stock Company Chicot116310.21518/1561-5936-2019-11-54-60Original ArticleConstruct validation and reliability analysis of a questionnaire to evaluate the factors influencing pharmacy staff's recommendation of over-the-counter drugs in VietnamTranVan Denoemail@neicon.ruDorofeevaValeriya V.noemail@neicon.ruLagutkinaTatiana P.noemail@neicon.ruPeoples' Friendship University of RussiaCan Tho University of Medicine and Pharmacy1112201911546018032022Copyright © 2019,2019The purpose of this study is to develop a valid and reliable tool for assessing factors affecting recommendation of over-the-counter drugs from pharmacy staff. A total of 422 pharmacy staff took part in this study. Exploratory factor analysis, confirmatory factor analysis, and Rasch analysis were used to evaluate construct validity and reliability of a questionnaire. 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