In clinical practice we want to know the area of a part of this, i.e. "how likely is it that a random item will be in this range from here to here?" That is the CUMULATIVE distribution functionpic.twitter.com/uPZdiqLBqn
This is the legacy version of twitter.com. We will be shutting it down on June 1, 2020. Please switch to a supported browser, or disable the extension which masks your browser. You can see a list of supported browsers in our Help Center.
Better ways of thinking, feeling, and acting—around problems of meaning and meaninglessness; self and society; ethics, purpose, and value.
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
Add this Tweet to your website by copying the code below. Learn more
Add this video to your website by copying the code below. Learn more
By embedding Twitter content in your website or app, you are agreeing to the Twitter Developer Agreement and Developer Policy.
| Country | Code | For customers of |
|---|---|---|
| United States | 40404 | (any) |
| Canada | 21212 | (any) |
| United Kingdom | 86444 | Vodafone, Orange, 3, O2 |
| Brazil | 40404 | Nextel, TIM |
| Haiti | 40404 | Digicel, Voila |
| Ireland | 51210 | Vodafone, O2 |
| India | 53000 | Bharti Airtel, Videocon, Reliance |
| Indonesia | 89887 | AXIS, 3, Telkomsel, Indosat, XL Axiata |
| Italy | 4880804 | Wind |
| 3424486444 | Vodafone | |
| » See SMS short codes for other countries | ||
This timeline is where you’ll spend most of your time, getting instant updates about what matters to you.
Hover over the profile pic and click the Following button to unfollow any account.
When you see a Tweet you love, tap the heart — it lets the person who wrote it know you shared the love.
The fastest way to share someone else’s Tweet with your followers is with a Retweet. Tap the icon to send it instantly.
Add your thoughts about any Tweet with a Reply. Find a topic you’re passionate about, and jump right in.
Get instant insight into what people are talking about now.
Follow more accounts to get instant updates about topics you care about.
See the latest conversations about any topic instantly.
Catch up instantly on the best stories happening as they unfold.
In clinical practice we want to know the area of a part of this, i.e. "how likely is it that a random item will be in this range from here to here?" That is the CUMULATIVE distribution functionpic.twitter.com/uPZdiqLBqn
The symbol for calculating the area under a curve is this:pic.twitter.com/ljPDh9DSZk
So that gives us this formula:pic.twitter.com/bS5dXygWgP
At the far left (distant past), it is minus 1. At the far right (far future), it is plus 1. In the middle, at time "beta", representing mid-epidemic, it is zero.
It's not quite what we want. We need to rescale that result, so that it starts at 0% infected, not "-1" ends at only a fraction "p" infected, not 100%. Step 1. Add 1. That fixes the start to be 0, not -1. But the end is not 2, not p.
So Step 2. Multiply by p/2. This gives this formula.pic.twitter.com/cjmM6tFwFT
That's literally all there is to it. The right hand part says "normal distribution" The left hand part says "scaled to go from 0 to some proportion p"
All the phenomena being discussed in the formula are familiar to all of us. We just couldn't all read it when written in efficient mathematical terminology.
If readers had not skipped over the "mathsy bit" when reading about model predictions, would have quickly pointed out to those advocating the models, that there is no reason to think the downslope is anything like the upslope.
I don't get it. Nobody is disputing that normal curve is symmetrical. What people are disagreeing with is the choice of a normal curve to fit to the data points on the sigmoid of infection increase, when there's no expectation of symmetry on decrease.
I took it that that was his overall point; and the point of this tweet in the thread was that the assumption of symmetry was non-obvious because of the complex notation.
Yes Barry, thank you for raising this question of what I was rabbiting on about 8-) David is correct. If people knew that we were just fitting a Normal distribution to the curve of the epidemic, they would have laughed, and disbelieved the results of the modelling.
Surely the onset of an epidemic is analogous to an impulse within a maybe somewhat tuned high-Q system, with all the possibilities of ringing, overshoot, feedback from resonance, damping, etc.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.