The general way to do that correction is to look at actuarial tables for deaths by cohort. These models are obviously not 100% accurate, but they do take into a

The general way to do that correction is to look at actuarial tables for deaths by cohort. These models are obviously not 100% accurate, but they do take into account many factors, and are incentivised to be as accurate as possible as they determine the profitavility of life insurance. In this context, excess deaths are variations from these tables - more people from a cohort dying in a certain time period than expected.