"Liz Tuddenham" wrote in message
id.invalid...
Rod Speed wrote:

NY wrote
[...]
OK. So this all hinges on the fact that the birth rate (and maybe death
rate) varies throughout the year.

Yes, and all you need is the birth day to vary, the
death day doesn't need to to get the statistical quirk.

That makes sense. Birth rate is under human control (to some extent)
and shows annual peaks, but while death rate only shows general seasonal
trends. If the birth rate is peaky by calendar date and the death rate is
flat,
more of the deaths will be on days which coincide with birthdays - not
because there are more deaths on those days but because there is a
greater chance that each dead person had been born on that day.

Precisely.

but... if the death rate were also peaky and the peaks
didn't coincide with the peaks of the birthdays, the
effect could be reduced or even reversed.

Yes.

This could happen if voluntary euthanasia becomes more widespread.

There is already some less than random effect with death day quite
apart from the seasonal effect because presumably there is likely
to be fewer staff working on weekends when they are doing the
paperwork to decide to pull the plug on those who the relos
agree to have the plug pulled on. Not enough to cancel out
the much more profound spikes in the birth days tho.