A. Graphs of the relationship between Square root of wall area at Pi10 and FEV₁ (r = 0.636, p<0.0001) n=33 and B. RV/TLC (r = -0.736, p<0.0001) n=28. Each graph is shown with a fitted regression line. FEV₁and RV/TLC are expressed as a percentage of the predicted normal value.