The chart shown is couple of days out of date now. But even as posted the last couple of days start to show the beginning of slowing in the rate of acceleration. More recent data indicate a deceleration. But more data needed for confirmation.

Def starting to look like NYC rates are slowing but still plenty of trouble ahead even there.

You guys are arguing and getting confused about nomenclature.

# of cases (or # of deaths) is the original thing we're talking about. It is analogous to distance traveled in a car analogy.

the first derivative of that is # new cases (or new deaths) per day. This is analogous to velocity.

the second derivative is the rate of change of cases/deaths per day. Which is analogous to acceleration.

the third derivative is the rate of change of cases/deaths per day per day, which is analogous to something called "jerk" in our physical world, though it is not a commonly known term.

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If the number of new cases per day holds steady, this is analogous to your cars velocity holding steady. cases/deaths is neither accelerating nor decelerating in this case. the velocity of (# cases) is positive, but the acceleration of (# cases) is 0.

If we still have positive new cases per day, and the number of cases per day increases day-over-day, then the velocity of (# cases) is positive (and rising), and the acceleration of (# cases) is also positive (even if the rate at which the number of cases per day increases is slowing down, or negative "jerk").

Today, our number of new cases per day [velocity] is still increasing day over day (20353 yesterday, 19913 two days ago, 19452 three days ago), so we are accelerating. But the rate of increase (jerk) is slowing (barely, from +461 to +440). Similar for deaths, though that is spikier for recent days (largely because NY had problems reporting) so is jumping around a bit.

Soon (hopefully) the number of new cases per day will level off and then start to decrease. Once new cases per day is decreasing, we will be decelerating (but still positive velocity, or adding new cases).

At some point, our new cases per day will reduce to 0 (or close enough), and then our velocity will be 0, and our # of cases will stop increasing, i.e. our car will have stopped moving.

Of interest probably only to me - right now our jerk is negative as our acceleration is slowing. But since we can never achieve negative cases per day, at some point our deceleration will also have to slow to zero, and along that journey our jerk will go through zero and back to being positive (similar to the bottom graph here: https://en.wikipedia.org/wiki/Jerk_(...en_vitesse.svg), and then jumping to 0 as a step function if the virus is killed and no new cases. Stupid math.

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If you wanted to consider the "new cases per day" metric to be the primary one, then you could make the argument that it was decelerating, because it's velocity is decreasing. But this would be a very confusing way to consider the data, because it is already a rate, not a primary unit of measurement.

I’m not confused at all about the nomenclature. I am a mechanical engineer, and I took plenty of physics and dynamics courses. I fully understand acceleration and jerk. I understand about the number of cases being analogous to distance and the derivatives of each. I almost made that analogy myself.

However, as I mentioned, the post I was replying to that started all of this stated that it appeared that the number of new cases was accelerating. The number of new cases was not accelerating at that point.

More importantly, new cases per day can (and should) be considered and monitored as a primary unit of measurement for a very important reason: As you noted, the total number of cases never decreases. But the number of active cases will decrease at some point. And that is the the metric that is constantly referred to when people discuss “flattening the curve” so that we don’t overwhelm the system. And new cases is an early indication of active cases. It basically shows us a couple weeks in advance what will be happening with the active cases curve. It is the best/earliest indication of whether the measures being taken to flatten the curve are working as hoped.

It is not confusing to discuss the acceleration of the number of new cases. After all, new cases is just a number of cases that happens to have occurred in a day. It still just becomes a series of numbers just like active cases that we can take the derivative of to monitor its rate of change and acceleration.

Let me sum up:
- New cases/day still going up (increasing).
- "Rate" (derivative) of new cases/day going down (decelerating).

No.

Those two things:
1- "new cases/day still going X"
2- "rate (derivative) of new cases/day"

are both describing the same thing, the change over time of (new cases / day). They (the rate/derivative of new cases/day) are both (currently) going up in the US. Yesterday (new cases / day) went up +440, from 19913 to 20353 new cases/day. 2 days ago they went up +461, from 19452 to 19913 new cases/day. As of yesterday there were 164,435 total cases in the US.

The second derivative of (new cases / day), or the third derivative of (# cases), is currently (barely) going down, by -21 (new cases per day, per day).

Which can also be said as "the acceleration of (new cases / day), or the jerk of (# cases), is going down."

Your second statement would be correct if you said "Rate (derivative) of new cases/day is still going up, but is decelerating."

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Note probably only interesting to myself: the day that the third derivative went from positive to negative (I haven't calculated when that was, but it was probably in the past few days), is the inflection point of our curve. It is the point at which our quasi exponential growth stopped, and we started bending back over to the right, in what is known as a logistic curve, which exhibits that "S" curve shape.

Perhaps, but it is confusing to everyone else. As evidence, I offer every other post about this topic in this thread.

I guess it depends on if you're defining "the number of new cases" as an objective number (we had 1000 new cases yesterday), or as a rate (new cases / day). Just saying "number of new cases" and not "number of new cases per day" is part of what is causing the confusion.

The number of cases is still accelerating. The number of new (cases / day) is now (and only recently) decelerating.

I'm definitely not saying (new cases / day) isn't an important metric to discuss.

But if you're going to talk about the rate of a rate, or the acceleration of a rate, you (and everyone else) has to be extremely careful to always be talking about the same thing. It leads to massive confusion otherwise.

When talking about derivatives, it is much easier to always talk about the rates at their primal level, because they cannot be unpacked any further. There is no (useful) physical quantity for which (# of cases) is already a rate, unlike (cases/day).

Anyway, just my opinion. As long as everyone is on the same page, I don't really care what statistics and units we all talk about.

Looking at the number of new cases per day is useless, because we're bumping up against the number of tests that can be performed each day. If we can only test 20,000 people a day as of a week ago, and it takes around 5-7 days to get the test results back, we're going to see around 20k new cases a day until we start testing more.
Deaths per day is going to be more accurate

Was going to point out that as well, but I figured people had more than their fill of my posts on the topic.
I agree with that. I wouldn’t have brought up the acceleration of the number of new cases had it not been in reply to a post. But it is something I personally observe when looking at the curves.

Fair point, but hopefully that will be changing significantly as they keep ramping up test kit production and since they’ve developed a test that provides results in minutes.

I was just looking at no. of new cases then comparing it to what I remember from the day before, but…

Didn't until recently notice the button at top wowing the previous day's total, which is always greater than the total I ever saw, which is throwing off my estimation.

A link to a Financial Times page on the virus, along with a bunch of graphs illustrating the spread of the disease. You'l have to scroll down a bit to see the one for no. of cases, but it does show the rate of growth in the US slowing:

FT

No, I meant accelerating, and I was looking at number of new cases; but that doesn't mean I was correct. Or now think I was correct. Glad to be wrong.


--klez

Sorry I am not at all confused either. As with Ep, who I have been agreeing with, I am also an engineer, CHE for me, but also have a degree in Physics and a minor mathematics.

Rather than speak in derivatives and seconds, heck to really analyze we should be working in partial derivatives w.r.t. time and patient age at least. But this will only confuse and daze (had to get some LZ in there) most readers. Just look at the log charts because the bend is easier to see

Number of deaths will always lag, both going up and even more so when declining. Also the time is now a day or even fifteen minutes now, those tests are just coming out.

Nice. I am also a huge Zeppelin fan.

I'm not confused, I just used bad wording.
What you were saying (dinesh, Eponymous) is in fact rather simple math concepts. But it derails the thread and is kinda boring. IMO.

Yeah, I agree. If things weren't so dead in here I might not have posted at all. I do like math and statistics, though.

Fair enough.
I do like them too, for the record.

The huge problem with all of the statistical analysis of this disease is the bad data. We just have zero idea how many unreported cases are/have been out there. Even with the faster tests, they're not going to test everyone, much less repeatedly. Still, as the tests are faster and cheaper, we'll likely see a huge spike in reported cases, as more people with mild symptoms get tested and precautionary tests catching people who are asymptomatic get dumped into the data stream.

We'll really only have good data on cases in the aftermath, imo. Death rate and/or hospitalization rates may lag, and may not tell us everything we want to know, but are the currently the only statistics based on relatively reliable data, imo.

3000+ deaths and counting. Where did Mike Starr and his laughable comments disappear to?

Completely agree that data are the issue; both quantity and quality are varying. I still don’t like deaths as you will still have significant deaths well after peak challenges. Was well explained the the Whitehouse press briefing yesterday when talking about the death tail

New hospitalizations is likely the best real-time data point. Once new hospitalizations peak the demands on resources will decay. But even this data are changing since as hospitals reach capacity cases that would have been admitteded early on may not be sent home.

My 1st post on this 2+2 forum... I searched bing for wsop coronavirus and eventually came across this thread which I found to be a really interesting read. Thank you for everyone that has posted and participated in the discussion; a lot of great info (and of course some junk to be expected)!

I'm curious about the impact on the WSOP... I have an airbnb reserved for 6 weeks which I booked in early February. The rental unit owner has a relative working at the Rio and expects it to continue as scheduled. If they keep it I will likely play the series (similar to how I played a local tournament series until they cancelled it in mid-March). They had guarantees and had to add significant prize money; it was a great EV!

One question I have is if we play the WSOP and some of us catch the virus and die from it, can our spouse sue Caesar's (since they own Rio now)? I need to calculate my EV and I think it should be part of the EV calculation ;-)

In all seriousness, I believe the ownership of the WSOP need to seriously consider the likelihood of this virus spreading unnecessarily due to continuing as scheduled with the biggest poker series in the world.

This thread has a lot more specific to WSOP

https://forumserver.twoplustwo.com/2.../index135.html

The WSOP is not happening

>1k dead today alone; you must patiently wait a few more days, i.e. >3-wks for 'Starr' to return;

Lots of us Egg-in-ears hanging out here (BSEE-power/machinery) .. no surprise with the language and detail of the posts!!

I love 'real world' comparisons when trying to explain 'complicated' topics. Thus my skeptical (perhaps clouded) view of the 'rates' without knowing other factors, mainly total tests. The car analogy is a good one ...

If we look at each hospital (reporting entity) as a car on the road, there have been more and more cars on the road each day ... adding to the total miles driven by all cars (cases). We don't give each car the same amount of gas (tests) but we do give each car more gas than the day before (more tests available). Some cars don't use all their gas every day but can choose to use yesterday's gas today as deemed necessary.

What we don't know is how long each car spends idling (negative test, can't 'drive' any miles). What we also don't know is whether or not a car 'wanted' to drive further the day before, but didn't have any gas, so those miles get driven the next day.

If a hospital wanted to test 50 people but only had 30 tests they 'had' to wait until the next day to test those 20 ... but now tack on another 50 people who need testing. But today they have 60 tests for 70 people ... and so on.

My friend's sister was in ICU for over a week about a month ago (post cruise). Her symptoms started 2 weeks before the ICU visit (one week post cruise). They finally tested her on her last day in the ICU .. negative, really?

What I'm hoping for is that there's eventually a way to test 'everyone' and hopefully prove that we've all been exposed ... got through it apparently ... and start releasing people back into society. It's almost like the movies where we all get branded CV19 to prove that we are 'OK'.

Not that it will be avoidable, but we certainly don't want to be looking over our shoulder for this one. GL

Mike also makes wild claims at poker, too. Shouldn't be surprising.

Mike Starr should just come back to this thread and eat a big slice of humble pie, it’d make me feel a tiny bit better about humanity and people’s capacity to accept that they were dumb... however he like me and everyone else probably has more serious things to worry about now.