4 ms·

I think that using date-of-report is better for lay-people. Pro/cons: - There's a one time spike when the methodology changes = The data lags reality on the g

by rovolo 6y ago

I think that using date-of-report is better for lay-people. Pro/cons: - There's a one time spike when the methodology changes = The data lags reality on the ground (true for both date-of-report and date-of-death) + Past dates aren't updated, so there isn't a continuous bias to show a slowdown in the number of new deaths I think that the last point is the most important because it's super easy for people to misinterpret provisional data. People were talking about covid-19 not causing excess mortality because using date-of-death always shows a dip for the present: https://twitter.com/TylerMorganMe/status/1248452375162925057 https://twitter.com/TylerMorganMe/status/1248452375162925057 You can also see the same thing in the top comment on this Euromomo thread: https://news.ycombinator.com/item?id=22866238 https://news.ycombinator.com/item?id=22866238 > Another very surprising thing is to see no excess mortality in Sweden, a country criticized for a laxer strategy against COVID-19. I was not expecting to see that. That was week 14 for https://euromomo.eu/graphs-and-maps/ https://euromomo.eu/graphs-and-maps/ . In fact, week 14's excess death z-score for Sweden was in the "very high excess" category after the data was collected.

pacala 6y ago
Please don't cite euromomo as a source: * They stopped graphing the per country raw numbers, which makes it impossible to put things in perspective: what is the comparative excess mortality per million people? * They use deceptive graphs that do not start yaxis at zero * They refuse to publish the raw dataset for independent processing.
- rovolo 6y ago
  I wasn't using euromomo as a source, I was using a thread on euromomo as an example of faulty interpretations of provisional date-of-death data.
AnthonyMouse 6y ago
There is a third option here. Don't publish data until it's collected. This means you don't publish data for deaths on a date until all the deaths on that date have been reported. Then you don't have to retroactively update anything because you didn't publish numbers before they're finalized. This option is clearly better than publishing date of report as date of death, because doing that is inaccurate. The data is really from events a week or more ago when you think it's from today, and you can get clusters like this when many reports come in at once. The disadvantage is that you then have newer data that isn't being published because it isn't completely in yet. But if you are going to publish incomplete data then it should still be date of death and the dates without full reporting should be annotated so that people understand that they're looking at incomplete data -- which they are, so it's very important for that to be understood.
- rovolo 6y ago
  > don't publish data for deaths on a date until all the deaths on that date have been reported Based on the animation I linked, it takes around 15 weeks for an apparent decrease in pneumonia deaths to rise to a normal number. 15 weeks ago was Feb 4. (Granted, pneumonia death data collection in normal times will be different than covid-specific data now). The numbers do get more accurate with time though. There is a trade-off between accuracy and timeliness.
- vharuck 6y ago
  It's a sliding scale between immediacy and accuracy, with a very high upper length of time for perfect accuracy. I work with death record statistics for a state government, and our reports use data from 2 years ago. A big reason is gathering reports for residents who died in other states. I know the CDC has a good system for sharing infectious disease diagnoses (https://wwwn.cdc.gov/nndss https://wwwn.cdc.gov/nndss). I don't know if there's a similar rapid-collection system for death records. We usually don't need to track deaths with this urgency. A possible compromise is to model a delayed reporting factor. Not sure if there could be a good enough model, though.
Tagbert 6y ago
Lay-people don’t really dig into the data and don’t compare i dates for changing stats. Tracking deaths by date of occurrence is much more useful than date of report, even if it means that you have to restate figures sometimes. We see that happen a lot with economic figures where they restart the previous month or quarter’s stats.
- rovolo 6y ago
  Restating the figures isn't necessarily bad. The issue with mortality revisions is that they're always revised upward; whereas the economic revisions can go either way. Using date-of-death introduces a consistent bias where recent deaths are undercounted compared to earlier deaths. People care about whether deaths are currently slowing or increasing. Date-of-report may be inaccurate, but it doesn't bias the trajectory of deaths consistently in either direction.

by rovolo 6y ago

pacala 6y ago

Please don't cite euromomo as a source: * They stopped graphing the per country raw numbers, which makes it impossible to put things in perspective: what is the comparative excess mortality per million people? * They use deceptive graphs that do not start yaxis at zero * They refuse to publish the raw dataset for independent processing.

rovolo 6y ago
I wasn't using euromomo as a source, I was using a thread on euromomo as an example of faulty interpretations of provisional date-of-death data.

AnthonyMouse 6y ago

There is a third option here. Don't publish data until it's collected. This means you don't publish data for deaths on a date until all the deaths on that date have been reported. Then you don't have to retroactively update anything because you didn't publish numbers before they're finalized. This option is clearly better than publishing date of report as date of death, because doing that is inaccurate. The data is really from events a week or more ago when you think it's from today, and you can get clusters like this when many reports come in at once. The disadvantage is that you then have newer data that isn't being published because it isn't completely in yet. But if you are going to publish incomplete data then it should still be date of death and the dates without full reporting should be annotated so that people understand that they're looking at incomplete data -- which they are, so it's very important for that to be understood.

rovolo 6y ago
> don't publish data for deaths on a date until all the deaths on that date have been reported Based on the animation I linked, it takes around 15 weeks for an apparent decrease in pneumonia deaths to rise to a normal number. 15 weeks ago was Feb 4. (Granted, pneumonia death data collection in normal times will be different than covid-specific data now). The numbers do get more accurate with time though. There is a trade-off between accuracy and timeliness.
vharuck 6y ago
It's a sliding scale between immediacy and accuracy, with a very high upper length of time for perfect accuracy. I work with death record statistics for a state government, and our reports use data from 2 years ago. A big reason is gathering reports for residents who died in other states. I know the CDC has a good system for sharing infectious disease diagnoses (https://wwwn.cdc.gov/nndss https://wwwn.cdc.gov/nndss). I don't know if there's a similar rapid-collection system for death records. We usually don't need to track deaths with this urgency. A possible compromise is to model a delayed reporting factor. Not sure if there could be a good enough model, though.

Tagbert 6y ago

Lay-people don’t really dig into the data and don’t compare i dates for changing stats. Tracking deaths by date of occurrence is much more useful than date of report, even if it means that you have to restate figures sometimes. We see that happen a lot with economic figures where they restart the previous month or quarter’s stats.

rovolo 6y ago
Restating the figures isn't necessarily bad. The issue with mortality revisions is that they're always revised upward; whereas the economic revisions can go either way. Using date-of-death introduces a consistent bias where recent deaths are undercounted compared to earlier deaths. People care about whether deaths are currently slowing or increasing. Date-of-report may be inaccurate, but it doesn't bias the trajectory of deaths consistently in either direction.