Demographic drift
\ˌdɛməˈgræfɪk\ \drɪft\
The gradual change in the types of people making up a given population (such as the employees of a company) over time. This can happen, for example, due to shifts in business focus, company mergers, or changes in sales channels for insurance products.
For example, a car manufacturing company that once employed many manual workers may now rely more on robots operated by skilled engineers. This shift in workforce composition is an example of demographic drift.
In pensions, demographic drift means that the characteristics of plan members can change over time. Older retirees may have very different health and lifestyle profiles compared to younger members. So, using the mortality experience of older retirees to set longevity assumptions for younger members could lead to inaccurate liability estimates.