ONE of the most reliable and informative sources of mortality data over the past year has been the Institute and Faculty of Actuaries’ weekly mortality monitor report. It shows weekly and cumulative mortality for the year, and unlike the ONS, adjusts for population size and age so we get a truer reflection of how the current trends compare with the past.
Last week the report showed that the trend of deaths in 2021 has been so low since mid-March that all the excess deaths in January and February had been almost cancelled out and cumulative standardised mortality stood at just 1.1 per cent above the ten-year average (see graph below).
At Lockdown Sceptics [where this article was first published yesterday] we were waiting for the moment when, at some point in the next few weeks, this figure would hit 0 per cent so we could announce that, despite the winter Covid surge, 2021 was now officially a low mortality year with below average age-standardised mortality.
However, it appears that moment now may never come, as unexpectedly this week the IFoA changed the baseline on its key chart. The ten-year baseline is gone, and in its place is a straight comparison with 2019.
The important thing to know about 2019 is it is the year with the lowest age-standardised mortality ever (see below).
So now, rather than mortality in 2021 being around 1 per cent above the ten-year average, it is suddenly ‘4.6 per cent above 2019’ (see graph below). The ten-year average line has vanished so no comparison can be made with it.
This major change in baseline – which is a big deal when producing statistics for keeping track of trends – is not acknowledged. A sign that the change may have been made without due care can perhaps be seen in the stray word ‘the’ left in the heading from when it was edited, so that in place of ‘compared to the 2011-2020 average’ it reads ‘compared to the 2019’.
The only explanation we are given is: ‘We use 2019 as the comparator as this is consistent with the excess deaths calculation above.’ It’s true that throughout the pandemic period the mortality monitor team have used 2019 for their excess deaths calculation, yet nonetheless they’ve used the ten-year average in the cumulative mortality chart. Why the sudden change? If they wanted now to show the cumulative trends relative to 2019, why not produce charts showing both?
It is frustrating that this change has been made just as their figures were poised to show 2021 heading into negative territory compared with the ten-year average. Even more frustrating is that the baseline is now the least deadly year in history.
The IFoA explain in previous reports that they use 2019 for their excess death calculation because they consider it to be the most accurate comparator for deaths ‘in the absence of a pandemic’, since ‘2019 and 2020 had similar mortality experience for weeks one to 12’. However, that doesn’t allow for the fact that 2019 was anomalously low even for recent years, not least because of a very mild winter flu season. It also doesn’t explain why they have suddenly changed the baseline in one of their key charts, making it impossible to continue keeping track of the trend against the last decade.
Lockdown Sceptics has contacted the Institute to query the reasons for the change and ask for the original baseline to be reinstated. I will update this post if we get a reply.
This article first appeared in Lockdown Sceptics on May 26, 20201, and is republished by kind permission