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JULY 18th: 
.
(ONTARIO COVID-19 Rt)
Keep reading to play an INTERACTIVE GAME where I will address SEVERAL Rt misconceptions
REGIONAL METRIC
Rt / Provincial Map
( https://arcg.is/SuGLr )
...1/19
. (ONTARIO COVID-19 Rt)Keep reading to play an INTERACTIVE GAME where I will address SEVERAL Rt misconceptionsREGIONAL METRIC Rt / Provincial Map( https://arcg.is/SuGLr )
...1/19
Day 1: 100 new cases reported
Day 2: 100
...
Day 60: 100
What’s the Rt on day 60? /2
Day 2: 100
...
Day 60: 100
What’s the Rt on day 60? /2
If you said 1.0, you’d be correct. There is no growth in cases so this has to be true. /3
Day 1: 100 new cases reported
Day 2: 101
Day 3: 102
...
Day 60: 159 (because 1 new case ADDED each day - and no, it’s not 160!)
What happens to Rt over time? /4
Day 2: 101
Day 3: 102
...
Day 60: 159 (because 1 new case ADDED each day - and no, it’s not 160!)
What happens to Rt over time? /4
Always above 1.0 but decreases is correct. This is because the percentage increase decreases since there’s more total cases. But since there’s growth, it’ll NEVER go lower than 1.0... But it’ll hit 1.0 eventually... At about the 4 month mark. Day 60 it’s 1.02. /5
Day 1: 100 new cases reported
Day 2: 99
Day 3: 98
...
Day 60: 41 (because 1 new case LESS each day)
What happens to the Rt over time? /6
Day 2: 99
Day 3: 98
...
Day 60: 41 (because 1 new case LESS each day)
What happens to the Rt over time? /6
Under 1.0 but decreases is correct. This is because the percentage decrease increases. By day 60 you’d be at 0.92. /7
Day 1: 100 new cases reported
Day 2: 101
Day 3: 102
...
Day 60: 180 (because 1% increase each day)
What happens to the Rt over time? /8
Day 2: 101
Day 3: 102
...
Day 60: 180 (because 1% increase each day)
What happens to the Rt over time? /8
The Rt will remain at 1.04 indefinitely. Rt stationary is linked to a common percentage increase. /9
Day 1: 100 new cases reported
Day 2: 100^1.01 = 105 (i.e. 100 to the power of 1.01)
Day 3: 105^1.01 = 110
...
Day 60: 3957
What happens to the Rt with exponential growth? /10
Day 2: 100^1.01 = 105 (i.e. 100 to the power of 1.01)
Day 3: 105^1.01 = 110
...
Day 60: 3957
What happens to the Rt with exponential growth? /10
Tricky. Increases. Not steadily. But spends a little less time at each successive Rt as days go up. By day 30, Rt = 1.24. By day 60, it’s up to 1.33. By day 90, my computer crashed. Seriously. This is what Florida experienced in all of June (i.e. 500 to 15 000). Frightening. /11
Day 1: 100 new cases reported
...
Day 60: XX
Rt constant at 0.9. How many cases reported on day 60? /12
...
Day 60: XX
Rt constant at 0.9. How many cases reported on day 60? /12
Correct answer is 22. /13
Day 1: 100 new cases reported
...
Day 60: XX
Rt constant at 0.8. How many cases reported on day 60? /14
...
Day 60: XX
Rt constant at 0.8. How many cases reported on day 60? /14
Correct answer is 5. Rt of 0.8 is a nice value. /15
Day 1: 100 new cases reported
...
Day 59: 1
Day 60: 0
What constant Rt achieves this? /16
...
Day 59: 1
Day 60: 0
What constant Rt achieves this? /16
0.7. Very achievable. @DFisman likes prolonged Rt of 0.7 for a reason. /17
LAST QUESTION, but a big one COVID-19 has an R0 of 2.8. That is the R naught value, or the Rt at time 0 without any mitigation. If we had 1 case today, how many new daily cases would there be in one month if Rt remained 2.8, or equal to R0? /18
17,287. Now imagine if your starting number was 100 when Rt became 2.8: 41% of Ontarians would be infected in 30 days.
SHARE the opening tweet with others so they can play this game too and learn what Rt tells us
And let me know how you did by commenting below
SHARE the opening tweet with others so they can play this game too and learn what Rt tells us And let me know how you did by commenting below
