A-C. Estimated effects from the APC model for asthma incidence rates.

<p>Fig 2A represents the age-specific incidence rates, referred to the reference period 1975; Fig 2B represents the merged period and drift effects (rate ratios): the linear increasing trend is given by the drift, while deviations from linearity (curvature) are determined by the period effect; Fig 2C represents the birth cohort effect. The arrow in B indicates the calendar period when the incidence of asthma has begun to level off. The respective regions surrounding the lines provide the 95% confidence intervals.