For HAI: 1) Is this 50% interesting? 2) Can I relate it with airplanes? 3) Is it possible to put bad jokes in the script? 4) And to implement Newark Airport bashing and brick video refusals in it?
Thanks! Especially hearing Reading in there as my stomping grounds and seeing the plane on the runway as a kid. Full circle now as a doc. Hang in there everyone!
As a Medical Laboratory Scientist (AKA a Lab Tech), I’m so happy you mentioned us. Not only are we doing COVID tests, but all other lab tests, including chemistry, blood transfusion, and microbiological testing. We really are vital in healthcare, yet I can count on 1 hand how many times I’ve seen people thank laboratory workers.
I wonder if this is an election time propaganda channel. Doesn't tell you cost or why only a fraction of US population is tested and why Trump doesn't have money enough for masks.
*Sees title* Oh cool looks like non-airplane related Wendover video. Literally not even 4:00 minutes in: "....Quest Diagnostics uses planes..." Of course they do 😂
Hi Wendover, you got your probability numbers wrong at 7:59. You've assumed that each pool of four can only contain 1 positive case, but there's the possibility that multiple within a pool of four contain positive cases. As such, with 25 pools of four and an 8% positivity rate, you would expect ~72% of pools to contain 4 negative results (0.92^4), meaning ~28% of pools would have at least 1 positive case. With 25 pools, that comes to about 7 pools. So your total number of utilized tests would be 25 + 7x4 = 53 (more efficient than the 57 you calculated). The magnitude of the error grows when you assume a 20% positivity rate; you would expect ~41% of pools to contain 4 negative results (0.8^4), meaning ~59% of pools would have at least 1 positive case. With 25 pools, that comes to about 15 pools. So your total number of utilized tests would be 25 + 15x4 = 85 (much more efficient than the 105 you calculated, and /still/ more efficient than running each test individually). The positivity rate at which pooling into groups of 4 no longer is more efficient than individual testing is actually 29.3% positivity rate. At that rate, 25% of pools would contain 4 negative results, meaning 75% of pools would have at least 1 positive case. With 25 pools, that comes out to 18.75 pools. So your total number of utilized tests would be 25 + 18.75x4 = 100
I was planning to check this exact thing myself but I guess you just saved me from running the numbers. That said I do wonder though if there might be room for improving pool testing efficiency, with careful planning you could probably use the same low risk samples in multiple different pools. Then if you get a few positive pools assuming you don't get too many or just a case of statistical bad luck that happens eventually based on which pools returned positive it should be possible to lead it back to which samples caused that. A nice theory and actually getting that approved in production is probably a nightmare in the medical field however, but given the sensitivity of those PCR tests I wouldn't be surprised if it could work.
That's right. It is also what I assume. In short, you don't know which pools will come back positive. So, it is the worst care scenario, when the positive samples spread evenly.
Go develop vaccines or something you smartass! I bet you could contribute positively to the fight against coronavirus loser! You shouldn’t be wasting your talent nerd!
@@extrastuff9463 actually this has already been put into theory. I think the way to minimize the number of tests need is to have batches of 1/(percentage of positive tests) However this percentage is difficult to estimate in every population so usually you should have batches a bit smaller than that. But for example if you have 4% and batch by 25, 36% of batches are negative which is great and then you have a probability of 6,25% for the "negative tests so you could batch by 16 and have 36% of the batches come positive again and then test in batches of 10 etc.. (with just these Three rounds and then individual testing for the remaining you can find everybody's results with 0,37 test per person) From what I've found, with a 4% positivity rate, testing by batches of 25 then mixing, then 16, then mix then 10 then mix then 4 and you need 0.32 test per person to test everybody.
I'll add an explanation of that calculation. 1. We know we get 8% +ves, so that means that, on average, 92% of the individual tubes are -ve P(Individual, -ve)=92% 2. When we group them into batches of 4, the group tests positive if even one of them is +be. But it tests -ve only if every one of them is -ve (Remember this, this is important). So we see we can calculate the probability of the group being -ve* because all those tests are independent of each other**. We know when events are independent of each other, we can multiply the individual probabilities. So the chance of the grouping of 4 being -ve is (92%)^4. P(group, -ve)=(92%)^4 *** 3. We know a grouping can either be +ve or -ve. Since being positive and negative are mutually exclusive and a group can't be something other than +ve or -ve, we can simply subtract the probability of -ve results from the total probability to get the probability that a grouping will test +ve => P(group, +ve)=1-(92%)^4 The result the OP posted. We can't simply add the probabilities since they all aren't related. When it is appropriate to add and when to multiply is determined by the relationship of the different factors with each other (whether they're dependent or independent) we combine to get the final, compound probability. *We can multiply the probabilities to see get the final probability of the grouping being -ve but we can't do the same for calculating the probability of the grouping being +ve since there it takes just one to spoil the bunch. There could be 1 +ve, or 2+ves, or 3 +ves, or all +ves but we'd just get positive so the logic for calculating the probability that way is much harder. **We assume they're not from the same family or office, etc. The testing companies probably mix all the test tubes after collecting and tagging them to make sure the groupings are as random as possible and remove that source of bias from the data.
me: sees the title. Thinks: ah, this vid wont have airplanes right? Wendover starts talking about planes. me: bro HOW- (also the whole comment section is about this so-)
Would you quit posting these madeup quotes everywhere. I've seen you in like 3 different channels at this point. Your corporate self-help guru shit is not gonna get off the ground, buddy
7:58 Woah stop right there! You can't just multiply 0.08 by 4 like that! You need to discount the positive pools before continuing with the calculation. Use a binomial distribution with n = 4 and r = 0.08 to see that there's a chance of 0.716 to have no positive samples in a pool, so then a chance of 1 - 0.716 = 0.284 for a pool to be positive. 28% will be positive!
True, but I think since he was just showing that pooling saves number of tests at low positive rates, he wanted to make the numbers simpler for a general audience. He actually simply showed the worst case for number of tests given that 8% of the 100 tests were positive not the average case. With 28.3% positive rate in the pools, you need to test 28.3 + 25 times for 53.3 tests, which may sound strange to the average viewer because it isn't a whole number.
They do in that they let you know how much people in a certain area have covid, helping guide restrictions, though granted it's a lagging indicator. Personally it helps you because you're still contagious ~10 days after your symptoms resolve, plus if the test comes back negative it can help narrow down a different issue.
Most people: Yeah. We want to know what those guys could do that we couldn't. Trumpets: But...but...'Murica is so big and the population is so large. Koreans: Seoul is much larger than NYC and is more densely populated. Trumpets: But...freedom!
@Wimbely Parkersson-Davis It is not the whole world. It is very few people. Everyone else follows. And it is not for kicks. It is the roll out of UN Agenda 21/2030. This has been planned for decades.
Just want to say a big thank you for the many years of content. I’m someone who only recently discovered they are able to pursue further education such as university. Content creators like yourself have made learning new things such a gift. Anyways I’m Just a random stranger in Australia reminding you that you are awesome. I’ve also subscribed to curiosity stream just now haha so yeah .keep doing what you do
Love that you mention Elmira New York's airport. Worked there for 10 years, and I knew the Quest Diagnostics lady that came on a strict schedule every week. It was a great small airport.
12:18 “Demand [for testing] will be even higher than before” in the fall. 🤯 Demand is already very high now and we can’t keep up with it. It’s an 11 day backlog in Houston.
As a person who’s visited Newfoundland many times, and even been to gander. It is largely known that there are talks about closing the airport for years now.
It's so awesome to watch the old wendover videos recommended and then the new videos, being able to IMMEDIATELY seeing the amazing improvement in quality! cheers!
Still waiting for “The logistics of air travel over China’s geography” edit: Great video! After reading the other comments I realized I was just adding to the Wendover cult so I should actually say something useful😉
My local church just had an outbreak. In the last week 15 people have been tested positive. My wifes grandma was one of them and was very ill. I took her to the hospital and they outright refused to test her because they said her symptoms weren't "covid specific". After arguing for 20 minutes and demanding her being tested to the point of them threatening to have me removed. A doctor finally said he would do it and of course she tested positive and now a week later she is struggling at home. I was directly exposed because I had to drive her to the hospital and I've been sick ever since. I've been turned down from 5 different places so I quit trying. I've been hospitalized 3 times in the last 5 years because I have really bad asthma. I'm now at home with my wife and we are self quarantining and I'm not doing well myself. My O2 has dropped to about 94 and I've had a pretty high temperature for about 4 days. Talked to the health department today and they said I dont need tested! I would have never believed this situation could ever happen and when I see people say similar shit online I usually assume they're just trying to troll people. One of my wifes friends was at the church and tested positive. They refused to test her husband and 3 children because they dont have symptoms but deemed all 5 COVID POSITIVE and the health department called her husbands work and said he was positive and cant work. He has no symptoms and was never tested. It's an absolute shit show and the responses are all over the place. So me, my wife, her grandma and mother probably all have it but cant be tested.
Hey Sam, I am working for a covid testing company in Germany. Case numbers dropped here, just as the prices for the PCR. Right now, the company is planning to test US samples in Germany by using overnight shipping from the US into our lab. Sounds ridiculous but it is worth the effort and high shipping cost for us
I get that this is a super serious virus and it could potentially kill me or someone I love... But I can't get over the swabs getting rammed up my nose. I had a severe flu when I was young and they did that technique and I think I'm scarred for life. Worst experience ever!
To a similar note, at Beijing Airport they pool-test those swabs for explosives. A group of 20 or so people were gathered together at the entrance to the terminal building, security used a single swab to all of us and after the machine said it's negative, they let all of us proceed into the airport building. When I think about that, I'm now wondering if it's possible to spread the traces of whatever they're looking for to other people via the shared swab...
6:27 That woman’s hairstyle is one of the most complicated I’ve ever seen. I have no idea how you would even begin to put something like that together.
umop apIsdn Well that explains why I’ve never seen it. I’m not American. To my hairstyling uneducated eyes, it’s incredibly complex. To you, it may not not be.
You should do a video if you can on the logistics of the "bubble" that NHL and/or NBA are utilizing to prevent the spread of COVID-19 within players and other staff.
My wife's research group has developed a rapid and cheap test based on Lamp (loop mediated isothermal amplification) that is cheap to produce and can be used at PoC (instead of shipping dangerous samples all around the country). Just saying there are alternatives to PCR.
There is another pooling technique I heard about which is faster and even more efficient. If you split each sample you can then include that same sample into multiple pools. Do a little sudoku on the results and you will know which sample was infected without needing to retest any of them. It was claimed that you can get 100 results from 10 samples this way. I suspect that the issue with high positivity rates mentioned in the video would modify that ratio in a similar way.
Great video but a quick a nitpick. RT-PCR does not directly quantify copies of viral RNA. Rather through reverse transcription you make complementary DNA (cDNA) based on the RNA sequence. You then amplify the cDNA using PCR.
Hi Wendover! I am a board certified medical laboratory scientist and a huge issue in any testing that happens is that there is a massive national shortage of qualified lab techs especially for this kind of PCR testing which is usually classed as high complexity. Just wanted to provide this context as to why the state of clinical labs in the country is the way it is
I really appreciate the effort you put into these videos! Think about it! How many articles he must have read how many people he must have talked to! Great work👍👍👍❤❤
all the point of care tests are slightly less accurate, but they do still catch all the infective cases, just not the non-infective ones. some of the point of care tests, like monoclonal antibodies on a piece of paper, are ridiculously cheap and easy to use, and they are still good enough to catch anything infective, and cheap enough to use every day. it's also not as logistically complicated.
"Central planning systems might have some inefficiencies in allocating resources". I am not very sure that slight enefficiencies mean massive famines in all countries with centrally planned economies(essentially there are centrally planning systems for everything) and being very behind in many technologies and at the end collapsing on itself, but yeah sure, slight inefficiencies
