4 ms·

Massachusetts (where I live) just retroactively restated their case and death data by test/death date vs. reporting date so it more closely aligns to when a per

Massachusetts (where I live) just retroactively restated their case and death data by test/death date vs. reporting date so it more closely aligns to when a person was experiencing sickness or death. I find it far more useful now. The curve is now smoother, and you can see just how lumpy reporting timing was making daily releases of numbers. It has the knock on effect of making the numbers for the last seven or so days liable to change every day, but it’s still a better picture of what’s going on. This should be the norm.

sanderjd 6y ago
Colorado includes all of this information. It is useful to see it in different ways. But I have definitely found the deaths-by-date-of-death to be the most useful (it is also the most encouraging).
- koheripbal 6y ago
  > I have definitely found the deaths-by-date-of-death to be the most useful Tracking deaths is actually the worst, most lagging indicator. It takes a very long time to die. The most useful was the CDC tracking cases-by-illness-onset, that gave you a great understanding of what the trend line really looked like over the last couple of days.
  - sanderjd 6y ago
    All indicators have pros and cons. Deaths by date of death is the most lagging indicator, which is bad for in-the-moment decision making, but it is also the most direct measure of the thing we should care most about, minimizing death-causing infections. So you can look at a graph of deaths by date, and if it is way down (like it is in Colorado right now), then you know that things were going well over the last few weeks. This doesn't give us any data on how well we're doing now, during our partial re-opening, but it will give us that information over the next few weeks, in a way that we can compare with what we were doing over the last few weeks. Cases by onset date is pretty good too, but there is this period of some unknown number of days where it is misleading because it is too incomplete. The Colorado tracker shades ten days as "potentially unreported cases", but I always wonder how they chose ten and whether that's conservative or aggressive. The death by date of death has the benefit of not being incomplete in that way. Another problem I see with cases by onset date is that I don't really care that much about how many cases there are, not directly. If there were a huge number of cases, but no deaths, that would be a bummer because being sick sucks, but it would not justify our extreme reaction. What we care about are the deaths. So I like direct measures of that. Cases by reported date doesn't seem very useful at all, for anything. Percent positive tests by day is a similar measure that seems more useful. But I'm an amateur, this is just what I think is and isn't useful for reasoning about what's going on.
lsllc 6y ago
If you have been following daily reported death "headlines" for MA, it doesn't line up with the state's per-day graphs; see page 9 [0]. I assume they're investigating them and going back and updating the daily totals as the graph seems to lag a few days, but it's not clear to me what methodology they are using. They have been doing this for a while. [0] https://www.mass.gov/doc/covid-19-dashboard-may-19-2020/download https://www.mass.gov/doc/covid-19-dashboard-may-19-2020/down...
jariel 6y ago
That's called an 'epi curve' and it's a very common thing, but the data usually lags somewhat. 'Date of reporting of case' and 'date of onset of symptoms' are two different things, both useful. The epi curve has the problem that it always looks like cases are declining because the most recent few days are 'not filled in yet' by cases that have been reported. I don't think it's anti-scientific to report either way, so long as the dats is well represented.

sanderjd 6y ago

Colorado includes all of this information. It is useful to see it in different ways. But I have definitely found the deaths-by-date-of-death to be the most useful (it is also the most encouraging).

koheripbal 6y ago
> I have definitely found the deaths-by-date-of-death to be the most useful Tracking deaths is actually the worst, most lagging indicator. It takes a very long time to die. The most useful was the CDC tracking cases-by-illness-onset, that gave you a great understanding of what the trend line really looked like over the last couple of days.
- sanderjd 6y ago
  All indicators have pros and cons. Deaths by date of death is the most lagging indicator, which is bad for in-the-moment decision making, but it is also the most direct measure of the thing we should care most about, minimizing death-causing infections. So you can look at a graph of deaths by date, and if it is way down (like it is in Colorado right now), then you know that things were going well over the last few weeks. This doesn't give us any data on how well we're doing now, during our partial re-opening, but it will give us that information over the next few weeks, in a way that we can compare with what we were doing over the last few weeks. Cases by onset date is pretty good too, but there is this period of some unknown number of days where it is misleading because it is too incomplete. The Colorado tracker shades ten days as "potentially unreported cases", but I always wonder how they chose ten and whether that's conservative or aggressive. The death by date of death has the benefit of not being incomplete in that way. Another problem I see with cases by onset date is that I don't really care that much about how many cases there are, not directly. If there were a huge number of cases, but no deaths, that would be a bummer because being sick sucks, but it would not justify our extreme reaction. What we care about are the deaths. So I like direct measures of that. Cases by reported date doesn't seem very useful at all, for anything. Percent positive tests by day is a similar measure that seems more useful. But I'm an amateur, this is just what I think is and isn't useful for reasoning about what's going on.

lsllc 6y ago

If you have been following daily reported death "headlines" for MA, it doesn't line up with the state's per-day graphs; see page 9 [0]. I assume they're investigating them and going back and updating the daily totals as the graph seems to lag a few days, but it's not clear to me what methodology they are using. They have been doing this for a while. [0] https://www.mass.gov/doc/covid-19-dashboard-may-19-2020/download https://www.mass.gov/doc/covid-19-dashboard-may-19-2020/down...

jariel 6y ago

That's called an 'epi curve' and it's a very common thing, but the data usually lags somewhat. 'Date of reporting of case' and 'date of onset of symptoms' are two different things, both useful. The epi curve has the problem that it always looks like cases are declining because the most recent few days are 'not filled in yet' by cases that have been reported. I don't think it's anti-scientific to report either way, so long as the dats is well represented.