Visualizing age-period-cohort trend surfaces: a synoptic approach.

Mortality data from 1950 to 1986 in Australia have been used to exemplify a method of displaying trends by age and cohort in populations over time. The visual summary or synoptic method illustrated here is similar to a topographic map with age and calendar time as its ordinates. This method is complementary to conventional analyses of age-period-cohort data which lack a summary graphic view other than that provided by the trend in age-standardized rates or a three dimensional perspective plot. Mortality from ischaemic heart disease (IHD), lung cancer and motor vehicle accidents are used as examples of the method and illustrate its utility when dealing with different forms of mortality trend e.g. cross-sectional cohort, and mixed trends.