Finally a voice of reason

Discussion in 'Hangar Talk' started by Morgan3820, Mar 24, 2020.

  1. Tantalum

    Tantalum Final Approach

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    ^I can just imagine the Dale Gribble conspiracy theories
     
  2. Palmpilot

    Palmpilot Touchdown! Greaser!

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    Eliminating the rounding errors:

    100
    123
    146.37
    172.7166

    Linear would be this:

    100
    123
    146
    172

    What I'm waiting for is not a linear increase, but an exponential curve with a base of less than one. [Edited for accuracy.]
     
    Last edited: Mar 29, 2020 at 11:31 AM
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  3. Palmpilot

    Palmpilot Touchdown! Greaser!

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    More testing would do a lot to solve the squishiness of the numbers.

    By the way, the FACT that caseloads in some places have exceeded the available medical facilities is not "made up."
     
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  4. Tantalum

    Tantalum Final Approach

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    I'd be curious to know how many of the "active" cases require a hospital ventilator.
    My understanding is that the vast majority of people who get this don't need to be in the hospital, as, after all, there is no real known cure.
     
  5. azure

    azure Final Approach

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    Not correct. We are talking about the rate of increase (the increase per day) being a constant percentage of the current value. That IS exponential growth. If
    (increase per unit time) = (constant) x (current value)
    then
    value (as a function of time) is proportional to e^(constant x time).

    The "constant" might be a small enough number that it doesn't LOOK lilke exponential growth, at least in the short run, but it is.
     
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  6. timwinters

    timwinters Touchdown! Greaser!

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    voice of reason...yeah...right! as Bill Gates said:

    It’s very tough to say to people, ‘Hey keep going to restaurants, go buy new houses, ignore that pile of bodies over in that corner. We want you to keep spending,’ because there’s maybe a politician who thinks GDP growth is what really counts.
     
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  7. PeterNSteinmetz

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    Yes, perhaps easiest to just plot the log of the number of total cases. If that looks like a straight line, then it is exponential growth at a constant rate.

    As of the day before yesterday (when I last did this for the US data), it looked like a fairly constant exponential growth with a 2.5 day doubling time. There was a slight hint of a decrease in the slope, but nothing that appeared outside the range of random variation.
     
  8. azure

    azure Final Approach

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    That's what I've been doing for the Vermont data. Because the sample size is so small, there is a good deal of random variation, but the linear fit is fairly good and the doubling time is consistent with the national value (about 2.4 days, with no sign of flattening as of two days ago).
     
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  9. Tarheelpilot

    Tarheelpilot Ejection Handle Pulled

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    I would rather die free.

    We will get exactly what we are asking for in this country.
     
  10. PeterNSteinmetz

    PeterNSteinmetz Cleared for Takeoff

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    There is fairly good accumulating evidence that hydroxychloroquine shortens the duration of viral shedding to between 4-6 days.

    Whether such people are then immune is not presently measured, but that would be the normal result.

    If Covid-19 becomes a trip to the doctor and some illness for a week or two (like many viral illnesses), with a need to take medicine but recovery following, it is a much less dangerous thing.
     
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  11. timwinters

    timwinters Touchdown! Greaser!

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    BTW...I listened to an article yesterday about the 1918 flue...the stats from that era show that the economies of the cities that shut down quickly and stayed shut down until it was over recovered far faster afterwards than those that didn't.

    Yes...We are FAR REMOVED from 1918...but still...a data point.

    OTOH...I certainly don't understand why Chicago would outlaw running and bicycling.

    ???

    How is it that you can't stay over 6' from people doing this? Hell, I can't imagine it's possible to get within 6' of anyone while bicycling...
     
  12. Cap'n Jack

    Cap'n Jack Final Approach

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    Drafting.

    Yes, I'm yanking your chain, a little.
     
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  13. X3 Skier

    X3 Skier En-Route

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    Maybe Chicago riders are all pros:D

    upload_2020-3-29_9-6-38.jpeg
     
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  14. Sluggo63

    Sluggo63 Line Up and Wait

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    "Exponential" is not a "buzz word."

    You had better go back and reread your textbook before you start talking about 'exponential growth' again.
     
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  15. Palmpilot

    Palmpilot Touchdown! Greaser!

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    There's a recreational trail about a block from my house, and it's shared-use between bicyclists and pedestrians. It's not wide enough to be able to maintain six-foot separation while passing.
     
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  16. Palmpilot

    Palmpilot Touchdown! Greaser!

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    Amen. Even with my engineering background, I had misremembered the form of the equation until I was straightened out by one of Azure's posts earlier in the thread.

    https://en.wikipedia.org/wiki/Exponential_function
     
  17. Chip Sylverne

    Chip Sylverne En-Route

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    Fear is the poison of our lives.
    Do you have a cite? Because this isn't what I've been hearing anecdotally from friends in the medical community. I should say that I have read the Chinese article in Lancet, but have heard nothing official about the trials taking place in NY. Is that where your info is coming from?
     
    Last edited: Mar 29, 2020 at 11:43 AM
  18. lowtimer

    lowtimer Pre-takeoff checklist

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    Is it possible that exponential is being used because many people think it means x10 or squared?
     
  19. jbarrass

    jbarrass Line Up and Wait

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  20. murphey

    murphey Final Approach PoA Supporter

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    2 4 8 16 32 64 128 256 512 1024.....for those us in the software industry, powers of 2 (exponents) are tattoo'd in our brains.
     
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  21. azure

    azure Final Approach

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    In this context (pandemic), exponential is being used because it is accurate, at least in the early stages.
     
  22. azure

    azure Final Approach

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    I posted on Brian's board that over the last two days, the Vermont data is showing signs of flattening. If I take only the data from Thursday through Saturday, the doubling time appears to be 4.8 days. Still too early to say whether this is truly a trend, but it is somewhat encouraging.
     
  23. lowtimer

    lowtimer Pre-takeoff checklist

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    I understand that it is accurate, but using a term that many think means x10 or squared could cause a lot of misunderstanding.

    Kind of like what non pilots think when we talk about stalling the aircraft.
     
  24. Everskyward

    Everskyward Administrator Management Council Member

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    There is the common usage of the word "exponential", and the mathematical one. Pretty sure the one we have been hearing refers to definition 1.

    Screen Shot 2020-03-29 at 13.55.51.png



     
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  25. jimhorner

    jimhorner Line Up and Wait

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    What’s the basis for saying “many think means x10 or squared”? If many think that, than we have a serious issue with how math is being taught in schools.

    An exponential equation is in the form

    f(x) = ab^x

    This is basic algebra. They still teach algebra in high school these days, right?
     
  26. Salty

    Salty Final Approach PoA Supporter

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    And if x = 1 then it’s exponential and linear. :p
     
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  27. lowtimer

    lowtimer Pre-takeoff checklist

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    Yes there's a serious issue with math in this country. Algebra is still taught, but in most schools it is not required for graduation.
    Long division is to much for a lot of people applying for entry level jobs here.
     
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  28. Palmpilot

    Palmpilot Touchdown! Greaser!

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    In f(x) = ab^x, x = 1 would refer to only one point along the curve, because x is the variable, with a and b being constants.

    Due to the fact that it's been a long time since I've worked with this stuff, in an earlier post I had "exponential" confused with f(x) = ax^b, where the base is the variable and the exponent is a constant. (I have since gone back and corrected my post.)
     
  29. Salty

    Salty Final Approach PoA Supporter

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    The letters you choose for the variables is irrelevant. If b=1 it’s still linear
     
  30. Palmpilot

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    When you're graphing f(x) = ab^x, If b = 1, you not only get a straight line, it's a HORIZONTAL straight line!

    The formula for a linear function is f(x) = ax + b.
     
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  31. Checkout_my_Six

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    The problem with the news...they make it sound like it’s gonns stay exponential...it’s not ...and it’s not asymptotic towards infinity. It will taper to a normal distribution.
     
  32. tspear

    tspear Pattern Altitude PoA Supporter

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    And algebra is a common core requirement.
    In many states, parents and students could not hack it. So they pressured political leaders to kill it.

    Sent from my HD1907 using Tapatalk
     
    Last edited: Mar 29, 2020 at 6:29 PM
  33. Chip Sylverne

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    Fear is the poison of our lives.
    Well, yeah, but the only thing that will make it less efficiently spread is the development of herd immunity, if measures aren't taken to limit contact. That's a pretty gruesome natural experiment, the curve could remain pretty darn steep in a population with no previous exposure.
     
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  34. azure

    azure Final Approach

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    The one we have been hearing where? The use of "exponential" by epidemiologists when talking about the pandemic is most definitely definition 2.
     
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  35. azure

    azure Final Approach

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    If "it" means the total number of cases that have occurred, "it" will eventually flatten to a horizontal line. (Though in principle, the y-value of that line could be the entire population of Earth - probably not though, since many infections have not been counted as "cases".)
     
  36. Everskyward

    Everskyward Administrator Management Council Member

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    On the news.
     
  37. murphey

    murphey Final Approach PoA Supporter

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    Which is the first derivative of the polynomial ax^2 + bx + c, which is exponential.
     
  38. Salty

    Salty Final Approach PoA Supporter

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    ax+b
     
  39. azure

    azure Final Approach

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    2ax + b. But ax^2 + bx + c is quadratic, not exponential. The first derivative of an exponential function is exponential, as is the 2nd derivative, and ...
     
  40. Salty

    Salty Final Approach PoA Supporter

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    Oops, you’re right
     
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