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Bug in active detection? #33
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[Some thinking aloud] Since the passive detection delay is 2, we can potentially actively detect new infections that arise in the first unit of time of the duration of infectiousness of a passively-detected individual. This on average is 0.5 infections (birth rate being used is 0.5). Thus I would expect something like 0.25 active detections per passive detection, ignoring active-active chains of detection. Since the active detection delay is 2, and the latent duration is 1, any such actively-detected infection should arise in its own first unit of infectious time. Since infection times are uniform, this is an average of 0.25 new infections which could be actively detected after an active detection. On the other hand, if I passively detect the index case, there's a probability this leads to immediate extinction. That probability is 1/3 under these parameters. Which should decrease the marginal active detection probability because in 1/3 of simulations there's no one to actively detect. |
Maybe this isn't wrong but just deeply counter-intuitive? Fixing delays and rates, if I passively detect a case, on average
If I don't passively detect a case
So, the marginal proportion of next-infections passively detected isn't hugely affected by whether or not a particular infection is detected (we lose a small chunk of a small number to active detection). But the reverse is not true, because for every infection we miss, we get a lot more infections we could never actively detect. |
Paging @swo because my brain now hurts |
Agree that those will help make sure that the "problem" is actually just unintuitive emergent behavior. |
Signs pointing to bug, via 920c8a0 we can get a passive-passive chain when active detection probability is 100% and active detection delay is 0.0. |
I think this is OK? (Unless you meant that passive detection delay were 0?) Two people in a chain can be passively detected after they transmit. |
Right. The later infection is actually detected first. Generation-views hurt my brain. |
I bet this is related to #53. That bug would (sort of) make active vaccination behave as if it had a random delay from t_exposed that was 1 + Uniform(0, 3), so it would lose out to passive when it shouldn’t. |
Using #32, moving the active detection probability slider around has very little impact on the outcomes.
At 500 simulations, otherwise default settings, I'm seeing:
Why is active detection not happening?
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