blog:2020-03-22:covid-19_spread_part_ii
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blog:2020-03-22:covid-19_spread_part_ii [2020/04/12 11:02] – va7fi | blog:2020-03-22:covid-19_spread_part_ii [2020/08/07 13:03] (current) – external edit 127.0.0.1 | ||
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- | ====== COVID-19 Spread (Part II) ====== | + | ====== COVID-19 Spread (Part II) Updated |
<WRAP center round important 90%> | <WRAP center round important 90%> | ||
* I'm not an epidemiologist, | * I'm not an epidemiologist, | ||
- | * This was originally written on Sunday March 22nd. Since then, I've updated the numbers and added updates at the end of the post. | + | * This was originally written on Sunday March 22nd. |
</ | </ | ||
+ | |||
+ | <WRAP center round tip 90%> | ||
+ | * Jump straight to the [[# | ||
+ | </ | ||
+ | |||
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|<100% >| | |<100% >| | ||
| <fc # | | <fc # | ||
- | | $$N = \frac{2660}{1 + e^{-0.32(t - 21.1)}}$$ | + | | |
</ | </ | ||
\\ | \\ | ||
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====== April 12th Update ====== | ====== April 12th Update ====== | ||
- | It's been over a week since the last update and according to the numbers, it looks like we are off the Exponential curve and into the linear growth middle section of the Logistic curve: | + | It's been over a week since the last update and according to the numbers, it looks like we are off the Exponential curve... |
{{ : | {{ : | ||
+ | |||
+ | ... and into the linear middle section of the Logistic curve: | ||
{{ : | {{ : | ||
{{ : | {{ : | ||
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I am still very skeptical that these numbers are an accurate description of our current situation so I feel like I have to explain an apparent contradiction here: | I am still very skeptical that these numbers are an accurate description of our current situation so I feel like I have to explain an apparent contradiction here: | ||
- | <WRAP indent> | + | <WRAP indent> |
- | The quick answer is no. The way evidence works is not symmetrical. | + | The quick answer is no. The way evidence works is not symmetrical. |
- | * If you catch it, you can, with 100% certainty, say that there was (at least) one mouse. | + | * If you catch a mouse, you can, with 100% certainty, say that there was (at least) one mouse in the basement. |
* If you don't catch anything, you can't say anything with 100% certainty. | * If you don't catch anything, you can't say anything with 100% certainty. | ||
So back in March, the reported cases grew exponentially, | So back in March, the reported cases grew exponentially, | ||
- The infection is actually flattening out (I really hope and wish this is the case), or | - The infection is actually flattening out (I really hope and wish this is the case), or | ||
- | - The amount of testing we do is insufficient and we are not recording the actual spread of the virus (I suspect | + | - The amount of testing we do is insufficient and we are not recording the actual spread of the virus (this might very well be the case). |
It's hard to say exactly which of these it is because the provinces aren't releasing the daily number of tests they perform (or if they do, I haven' | It's hard to say exactly which of these it is because the provinces aren't releasing the daily number of tests they perform (or if they do, I haven' | ||
- | ^Province ^Cases ^Death ^Death Rate | | + | ^Province ^Cases ^Deaths ^Death Rate | |
^BC |1445 |58 |4.0%| | ^BC |1445 |58 |4.0%| | ||
^AB |1569 |40 |2.5%| | ^AB |1569 |40 |2.5%| | ||
Line 269: | Line 275: | ||
^QC |12292 |289 |2.4%| | ^QC |12292 |289 |2.4%| | ||
- | The number of cases and the number of deaths are reported daily. | + | The number of cases and the number of deaths are reported daily. |
+ | <WRAP centeralign> | ||
+ | \text{Death Rate} = \frac{\text{\# of Deaths}}{\text{\# of Reported | ||
+ | </ | ||
+ | |||
+ | Another way to think of this is: for every 100 reported cases, how many people | ||
+ | |||
+ | From this, we see that BC has 4 deaths per 100 reported cases, where as Alberta has 2.5 deaths per 100 reported cases. This suggests that there are a lot more unreported cases in BC since the death rates should be relatively similar across the country. | ||
+ | |||
+ | What we hear from the news also supports this: Alberta is being praised for the high number of tests they are performing (and their death rate is low) while Ontario is being criticized for the opposite (and their death rate is high). | ||
- | For this, we see that BC has 4 death per 100 reported cases, where as Quebec has 2.4 deaths per 100 reported cases. | + | Unfortunately, |
===== A Letter to Dr. Henry ===== | ===== A Letter to Dr. Henry ===== | ||
- | Yesterday, I sent the following letter to Dr. Henry: | + | Yesterday, I sent the following letter to [[bonnie.henry@gov.bc.ca |Dr. Henry]]: |
<WRAP box center 90%> | <WRAP box center 90%> | ||
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</ | </ | ||
- | And this morning, a [[https:// | + | And this morning, a [[https:// |
+ | |||
+ | Unfortunately, | ||
+ | |||
+ | ===== April 17th Update ===== | ||
+ | I finally found a key piece of data((The site I have been using just added the number of tests performed recently: [[https:// | ||
+ | |||
+ | Here's a summary of the four most populous provinces as of the end of yesterday: | ||
+ | |||
+ | ^Province ^Tests ^Cases ^Deaths ^Population (Millions) ^^Cases / Tests ^Death / Cases ^Tests / Million ^Cases / Million ^Death / Million | | ||
+ | ^BC |59185 |1575 |77 |5.111 ^|2.7% |4.9% |11580 |308 |15 | | ||
+ | ^AB |85502 |2158 |50 |4.413 ^|2.5% |2.3% |19375 |489 |11 | | ||
+ | ^ON |128093 |8961 |423 |14.712 ^|7.0% |4.7% |8707 |609 |29 | | ||
+ | ^QC |151510 |15857 |630 |8.538 ^|10.5% |4.0% |17745 |1857 |74 | | ||
+ | |||
+ | That's a lot of numbers so let's unpack this table a bit: | ||
+ | |||
+ | * The " | ||
+ | * The other columns are calculations: | ||
+ | * "Cases / Tests" is the percentage of tests that come back positive. | ||
+ | * "Death / Cases" is the number of death for every 100 **reported** cases. | ||
+ | * "Tests / Million" | ||
+ | * "Cases / Million" | ||
+ | * " | ||
+ | |||
+ | So let's compare these four provinces. | ||
+ | |||
+ | ==== Number of Reported Cases ==== | ||
+ | If we look at the total number of reported cases, it looks like BC is doing the best and Quebec is the worst: | ||
+ | * BC: 1575 cases | ||
+ | * AB: 2158 cases | ||
+ | * ON: 128093 cases | ||
+ | * QC: 151510 cases | ||
+ | |||
+ | If we take these numbers and scale them to take account of each provinces' | ||
+ | * BC: 308 cases / million | ||
+ | * AB: 489 cases / million | ||
+ | * ON: 609 cases / million | ||
+ | * QC: 1857 cases / million | ||
+ | |||
+ | It would be tempting to stop there, but the problem is that not every province is testing the same. This means that some provinces might have a more realistic view of the infection rate than others. | ||
+ | |||
+ | ==== Death Rate ==== | ||
+ | The first clue to this is to look at the number of deaths per hundred cases: | ||
+ | |||
+ | * AB: 2.3 deaths per 100 reported cases. | ||
+ | * QC: 4.0 deaths per 100 reported cases. | ||
+ | * ON: 4.7 deaths per 100 reported cases. | ||
+ | * BC: 4.9 deaths per 100 reported cases. | ||
+ | |||
+ | This time, the ranking is very different as BC went from being first to being last. There are a few different things that could explain this: | ||
+ | * Maybe in Quebec, Ontario, and BC, it's the most vulnerable population that contracted the virus, leading to more deaths. | ||
+ | * Maybe Alberta has unusually successful treatments for people infected. | ||
+ | * Maybe different provinces are not reporting their infected cases in the same way. | ||
+ | |||
+ | We would expect some variation, of course, but for BC to be #1 when it comes to having the fewer number of cases, and then the worst when it comes to the number of deaths / reported cases suggests that we are under-reporting. | ||
+ | |||
+ | ==== Number of Tests ==== | ||
+ | After over a month of looking at these numbers, we finally got access to the number of tests being performed. | ||
+ | |||
+ | * AB 19375 tests / million | ||
+ | * QC 17745 tests / million | ||
+ | * BC 11580 tests / million | ||
+ | * ON 8707 tests / million | ||
+ | |||
+ | Unsurprisingly, | ||
+ | |||
+ | Per capita, Alberta has tested 1.7 times more than we have so far. So it would be reasonable to estimate that if we had tested 1.7 times more, we could have found 1.7 times more cases, which would have brought our total from 1600 cases to 2600 instead. | ||
+ | |||
+ | |||
+ | ==== Positive Result Rate ==== | ||
+ | Another number that is very interesting to look at is the number of positive cases per 100 tests performed. | ||
+ | * A low number could mean that we are testing uninfected people just to make sure (health care workers for example). | ||
+ | * A high number could mean that we are testing people that are more obviously infected. | ||
+ | |||
+ | At any rate, There' | ||
+ | * AB: 2.5% | ||
+ | * BC: 2.7% | ||
+ | * ON: 7.0% | ||
+ | * QC: 10.5% | ||
- | Unfortunately, she doesn' | + | ==== Conclusion ==== |
+ | One of the main conclusions from this is that, as suspected, BC is behind on testing (and Ontario is worse) and until we start ramping up on testing, we just can' | ||
blog/2020-03-22/covid-19_spread_part_ii.1586714535.txt.gz · Last modified: 2020/04/12 11:02 by va7fi