Fig. 4From: Validation of the global lung initiative 2012 multi-ethnic spirometric reference equations in healthy urban Zimbabwean 7–13 year-old school children: a cross-sectional observational studyMean values expressed as a percent of predicted values according to African-American GLI2012 and Polgar spirometric reference equations for a FEV1 b FVC c FEV1/FVC d MMEFBack to article page