A question about trendlines from a fellow amateur: would it not be the case that any population shifts over time that are happening at a more or less regular rate (even a regularly *increasing* rate) end up being 'baked into' raw mortality figures? I understand the concept of a shifting population pyramid and an aging population, but unless there are some external factors (major shifts in immigration; war; etc.) wouldn't a trendline from a reasonably long period predict the immediate future fairly well? It seems to me that for the purposes of assessing excess mortality during what I call the 'Covid-response' period (starting in March of 2020) an extrapolated trendline should be enough to pick up major deviations. But this is all just my sense of how things should work, based on zero training or background in demographics! I'd love to hear your take on it, and on the Canada situation as I've described it.
Thanks for your feedback! Haven't had time to fully read your post but... my answer to your question is "jein" (German for yes and no).
"population shifts over time that are happening at a more or less regular rate (even a regularly *increasing* rate) end up being 'baked into' raw mortality figures?" - Yes, but modern population pyramids are not always "more or less regular".
"I understand the concept of a shifting population pyramid and an aging population, but unless there are some external factors (major shifts in immigration; war; etc.) wouldn't a trendline from a reasonably long period predict the immediate future fairly well?" No, not always - Because population pyramids are no longer nice and pyramidal looking, thus it can be counter-intuitively inaccurate/misleading, i.e. exaggerate or underestimate effects.
For example, there is a significantly greater number of 70-74 year-olds about to move into the 75-79 age group. Similarly there is a significantly lesser number of 50-54 about to move into the 55-59 age group. Ignoring these demographics would be misleading.
But seriously: numbers of births are one thing, but birth rates (number of births divided by number of potential mothers, maybe even considering age of mother at birth) are more informative. After a short baby-boom 2021/22, births in Ireland now seem on the way down as well, but maybe this can be explained by population structure.
Nice work, Witzbold! I would love to hear any feedback on my own attempt to make sense of Canada's (much less detailed) data:
https://thoughtsonacrisis.substack.com/p/mortality-mismatches-in-canada
A question about trendlines from a fellow amateur: would it not be the case that any population shifts over time that are happening at a more or less regular rate (even a regularly *increasing* rate) end up being 'baked into' raw mortality figures? I understand the concept of a shifting population pyramid and an aging population, but unless there are some external factors (major shifts in immigration; war; etc.) wouldn't a trendline from a reasonably long period predict the immediate future fairly well? It seems to me that for the purposes of assessing excess mortality during what I call the 'Covid-response' period (starting in March of 2020) an extrapolated trendline should be enough to pick up major deviations. But this is all just my sense of how things should work, based on zero training or background in demographics! I'd love to hear your take on it, and on the Canada situation as I've described it.
Hi Adam,
Thanks for your feedback! Haven't had time to fully read your post but... my answer to your question is "jein" (German for yes and no).
"population shifts over time that are happening at a more or less regular rate (even a regularly *increasing* rate) end up being 'baked into' raw mortality figures?" - Yes, but modern population pyramids are not always "more or less regular".
"I understand the concept of a shifting population pyramid and an aging population, but unless there are some external factors (major shifts in immigration; war; etc.) wouldn't a trendline from a reasonably long period predict the immediate future fairly well?" No, not always - Because population pyramids are no longer nice and pyramidal looking, thus it can be counter-intuitively inaccurate/misleading, i.e. exaggerate or underestimate effects.
Check out the Canadian population pyramids here:
https://www12.statcan.gc.ca/census-recensement/2021/dp-pd/dv-vd/pyramid/index-en.htm
For example, there is a significantly greater number of 70-74 year-olds about to move into the 75-79 age group. Similarly there is a significantly lesser number of 50-54 about to move into the 55-59 age group. Ignoring these demographics would be misleading.
Very thorough analysis, thank you!
Now do births for Ireland... :)
But seriously: numbers of births are one thing, but birth rates (number of births divided by number of potential mothers, maybe even considering age of mother at birth) are more informative. After a short baby-boom 2021/22, births in Ireland now seem on the way down as well, but maybe this can be explained by population structure.
Ha! that is exactly what I have been thinking lately - try to calculate birthrates for the different age groups :)