FEV1/FVC Ratio (Tiffeneau Index): Females, Age 20-29

What these numbers mean

A value around 0.866 is typical (50th percentile) for females in this age group. The middle 50% of the reference population fall between about 0.822 and 0.905; values below or above that central range sit in the lower or upper half of the distribution. Position in the distribution does not, on its own, indicate better or worse health for this metric.