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Don't these arguments apply equally well for manual contact tracing? There will be very significant false positives and negatives there too. I would expect tha

Don't these arguments apply equally well for manual contact tracing? There will be very significant false positives and negatives there too. I would expect that a contact tracing app can actually make a much more accurate list. Trying to accurately remember who I was near and for how long over the last X days is difficult (given that I'm not confined in my house, of course) Even with intensive manual research, working out who it was that cycled behind me for 5 minutes this morning or who I coughed next to at the cheese counter is going to be remarkably difficult. Apps can plausible cover some of those cases. We'll need to tune the alerts for acceptable precision & accuracy, as a function of the signal strength & duration of each contact, but that seems like a tractable problem, and again seems very similar to judging the risk of manually collected contact events. Despite all these possible inaccuracies, AFAICT contact tracing has been shown to be very effective, and is a well respected technique. I don't see anything here about how apps will be significantly worse. This assumes a significant install base of course, but I think that's tractable.

jerf 7y ago
"Don't these arguments apply equally well for manual contact tracing?" No. They mostly apply to manual contact tracing, certainly, but they do not apply equally well. A human being doing it is much smarter. They do take into account the fact that someone was on the other side of a wall. They are not limited by whether or not someone installed the app. They can use their brain to solve little local issues that the app can't even perceive which cumulatively add up to a huge difference. The app has a few advantages over the human, too, but I don't think it's that surprising at all that when it's all summed up and accounted for it ends up heavily Advantage: Dedicated Human. The modest advantages are trashed by the massive disadvantages.
- pimterry 7y ago
  I agree there's cases that humans will handle better, but there's also cases where the apps will do better too, and I wouldn't be surprised if it was a wash (soon hopefully we'll have some actual research on this!). For example, in most situations where you're near an anonymous stranger, manual tracing is going to have a lot of trouble. That's a _lot_ of cases. You're almost certainly not going to be able to hunt down the person you sat next to on the metro for half an hour, or a stranger who came into your shop to ask some questions yesterday. Apps plausibly could trace them. That's before you start thinking about simple forgetfulness. Who did you sit next to in the company meeting a week ago? Assuming people actually use contact tracing apps (TBC...), then many of those otherwise untraceable contacts can be picked up.

jerf 7y ago

"Don't these arguments apply equally well for manual contact tracing?" No. They mostly apply to manual contact tracing, certainly, but they do not apply equally well. A human being doing it is much smarter. They do take into account the fact that someone was on the other side of a wall. They are not limited by whether or not someone installed the app. They can use their brain to solve little local issues that the app can't even perceive which cumulatively add up to a huge difference. The app has a few advantages over the human, too, but I don't think it's that surprising at all that when it's all summed up and accounted for it ends up heavily Advantage: Dedicated Human. The modest advantages are trashed by the massive disadvantages.

pimterry 7y ago
I agree there's cases that humans will handle better, but there's also cases where the apps will do better too, and I wouldn't be surprised if it was a wash (soon hopefully we'll have some actual research on this!). For example, in most situations where you're near an anonymous stranger, manual tracing is going to have a lot of trouble. That's a _lot_ of cases. You're almost certainly not going to be able to hunt down the person you sat next to on the metro for half an hour, or a stranger who came into your shop to ask some questions yesterday. Apps plausibly could trace them. That's before you start thinking about simple forgetfulness. Who did you sit next to in the company meeting a week ago? Assuming people actually use contact tracing apps (TBC...), then many of those otherwise untraceable contacts can be picked up.