The pandemic made the method visible. Estimates of excess mortality for 2020 and 2021 differed by a factor of two or more depending on the baseline chosen, whether ages were standardised, and how the pre-pandemic trend was extended; the WHO's global estimate was nearly three times the count of reported COVID deaths. National offices have since changed their methods — the ONS adopted a new approach in 2024 that revised the UK's excess figures — and the changes moved the answers. Cause attribution has the same character. Certification practice differs between countries, automated coding has replaced manual coding at different times in different places, and the move to ICD-11 is slow and uneven, so a shift in a cause's share can be a change in coding as readily as a change in deaths. Late registration, as in England and Wales, adds a further lag. None of this means the counts are wrong; it means that the method is part of the result, and that comparisons across countries and across time have to carry it.