Age-period-cohort (or APC) analysis
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A common way to analyze historical mortality improvements is to break them down into three components: age, period and cohort.
Age effects reflect the fact that progress in reducing mortality may be concentrated amongst certain age groups. For example, in recent decades major improvements have been observed in those aged in their 50s, 60s and early 70s due to reductions in deaths from heart disease, whereas improvements have been lower at older (and younger) ages.
Period effects relate to factors that affect all age groups at a particular time – such as environmental, societal or economic factors. For example, mortality improvements across all ages were particularly high during the 2000s and have been much lower during the 2010s.
Cohort effects relate to the unique experience of a particular birth cohort. For example, individuals born during the late 1920s and early 1930s in the UK, described as the “golden cohort”, have seen particularly strong improvements in mortality.