Expressing the forced expiratory volume in 1-second (FEV1) as percent predicted (%Pred)* or standardized residual (SR)†
1a. Reference values for FEV1, in men of height 1.7 meters (5 feet 7 inches). Subjects A (a 30-year old) and B (a 70-year old) are on the lower 95% confidence limit, corresponding to 74%Pred and 63%Pred, respectively.‡
1b. Plot of the data from Figure 1a, expressed as SR. As can be seen, SR values remain constant, regardless of age.‡
* (measured / predicted) × 100
† (measured − predicted) / (standard deviation of the residuals); see text.
‡ Reproduced with permission from reference 15.