Ascertainment Bias closer to 3.0
Closed this issue · 3 comments
First, thanks for the code and making this project open. I'm using this for my effort to build a school re-opening calculator. Community prevalence is a key parameter.
With that said, I want to share my investigation into Ascertainment Bias.
Based on the CDC's October Seroprevalence data, I think the Ascertainment Bias for new cases/active cases is closer to 3.0.
I've written this up here:
https://github.com/chonghorizons/covid-estimators/wiki/Ascertainment-Bias
OPTIONS
- Do nothing.
- You might allow people to use 3.0 in the main chart.
- You might default to 3.0 or 5.0.
- (hardest) Pull in the state-by-state ascertainment bias numbers.
- For NY/NJ data, make adjustments for AscertainmentTotal (Total Infected/Total Tested Positive) and AscertainmentActive (ActiveInfected/ActiveTestedPositive)
- The seroprevalence data has high uncertainty, so you can't really do a first-differencing of the seroprevalence data waves.
- You might be willing to use a neighboring-state number. Or try to fill in information for some states using test-positivity as a regressor.
Again, thanks!!!
A small aside.
With 16million positive test cases (Dec 14, 2020), an ascertainment bias of 10.0 => 160 million cases. About 50% of the population. I think that's unlikely. We'd be close to herd immunity levels then.
With 16million positive, an ascertainment bias of 5.0 => 80 million cases. About 25% of population. That seems reasonable. Probably on the high range of what I think is real.
16 million positive and ascertainment bias of 1.0 => 5% of US population. I think that is not reasonable. So the importance of ascertainment is still important.
CDC Seroprevalence in Oct 2020.
Eyeballing the weighted average of the CDC seroprevalence suggests that the mid Oct 2020 seroprevalence (most recent data) was about 8% +/- 3%, suggesting about 26million infected.
The US positive test count (via Covid Tracking Project) was about 8 million then.
26/8 = 3.25 +/- 1.25%
@jsweitz we should probably put this in as a the new default (and take out 10). I have time this week to do this,
Deployed today in production