Day Trading Stocks & Futures
- Thread starter TraderRavi
- Start date
- Tags banknifty bnf daytrading nifty future
Any good new of flattening the curve as well as eradicating the problem needs applause by whichever state. Unfortunately, today in Karnataka, 1-2 cases have sprung up in several districts, where either in-laws of the infected are showing symptoms or unknown contact. Whatever the reason, the cases are not decreasing, although cases are increasing at a slower pace.
How false negatives are complicating COVID-19 testing
The majority of tests around the world use a technology called PCR, which detects pieces of the coronavirus in mucus samples.
As COVID-19 tests become more widely available across the US, scientists have warned about a growing concern: Many people with negative results might actually have the virus.
That could have devastating implications as a global recession looms and governments wrangle with the question of when to reopen economies shuttered as billions of people were ordered to stay home in an effort to break transmission of the deadly disease.
The majority of tests around the world use a technology called PCR, which detects pieces of the coronavirus in mucus samples.
But "there are a lot of things that impact whether or not the test actually picks up the virus," Priya Sampathkumar, an infectious diseases specialist at Mayo Clinic in Minnesota, told AFP.
"It depends on how much virus the person is shedding (through sneezing, coughing and other bodily functions), how the test was collected and whether it was done appropriately by someone used to collecting these swabs, and then how long it sat in transport," she said.
The virus has only been spreading among humans for four months and therefore studies about test reliability are still considered preliminary.
Early reports from China suggest its sensitivity, meaning how well it is able to return positive results when the virus is present, is somewhere around 60 to 70 percent.
Different companies around the world are now producing slightly different tests, so it's hard to have a precise overall figure.
But even if it were possible to increase the sensitivity to 90 percent, the magnitude of risk remains substantial as the number of people tested grows, Sampathkumar argued in a paper published in Mayo Clinic Proceedings.
"In California, estimates say the rate of COVID-19 infection may exceed 50 percent by mid-May 2020," she said.
With 40 million people, "even if only one percent of the population was tested, 20,000 false-negative results would be expected."
This makes it critical for clinicians to base their diagnosis on more than just the test: they must also examine a patient's symptoms, their potential exposure history, imaging and other lab work.
Timing is everything
Part of the problem lies in locating the virus as its area of highest concentration shifts within the body.
The main nasal swab tests examine the nasopharynx, where the back of the nose meets the top of the throat. This requires a trained hand to perform and some portion of the false negatives arises from improper procedure.
But even if done correctly, the swab may produce a false negative. That's because as the disease progresses, the virus passes from the upper to the lower respiratory system.
In these cases, the patient may be asked to try to cough up sputum -- mucus from the lower lungs -- or doctors may need to take a sample more invasively, when a patient is under sedation.
Daniel Brenner, an emergency physician at Johns Hopkins Hospital in Baltimore, described to AFP taking a test after performing a procedure called a bronchoalveolar lavage.
This was done on a patient whose nasal swab returned negative three times, but who showed all the signs of COVID-19.
Eventually, the patient's medical team placed a camera down his windpipe to examine the lungs, then sprayed fluid in and sucked out the secretions, which were then tested, resulting in a positive.
No perfect test
Uncertainty in clinical diagnoses is not new, and clinicians are well aware that no type of test for any condition can be considered perfect.
What makes COVID-19 different is its newness, said Sampathkumar.
"Most of the time when you have tests, you have test characteristics outlined carefully and warnings about tests interpretation," she said.
"We had no test for so long, and when we got the test, we started using it widely and sort of forgot the basics."
After being slow to start mass testing, the US has ramped up production and has tested almost 2.5 million people, with pharmacists now authorized to carry out the procedure.
But "the real fear of that is people who are given a false negative test and then decide that they're safe to go around their daily life and go out and expose people," said Brenner.
Much hope is placed on newly available serological tests which look for antibodies produced by a person's body in response to the virus and can tell whether a person was infected, long after they recovered.
They could also be used to help diagnose a person who is currently infected but whose PCR test results showed a false negative, by waiting a week or so for the body to produce its immune response.
"We are excited about the serologic test, but we don't know how well it will work and we are starting to study it," said Sampathkumar.
How false negatives are complicating COVID-19 testing
The majority of tests around the world use a technology called PCR, which detects pieces of the coronavirus in mucus samples.
As COVID-19 tests become more widely available across the US, scientists have warned about a growing concern: Many people with negative results might actually have the virus.
That could have devastating implications as a global recession looms and governments wrangle with the question of when to reopen economies shuttered as billions of people were ordered to stay home in an effort to break transmission of the deadly disease.
The majority of tests around the world use a technology called PCR, which detects pieces of the coronavirus in mucus samples.
But "there are a lot of things that impact whether or not the test actually picks up the virus," Priya Sampathkumar, an infectious diseases specialist at Mayo Clinic in Minnesota, told AFP.
"It depends on how much virus the person is shedding (through sneezing, coughing and other bodily functions), how the test was collected and whether it was done appropriately by someone used to collecting these swabs, and then how long it sat in transport," she said.
The virus has only been spreading among humans for four months and therefore studies about test reliability are still considered preliminary.
Early reports from China suggest its sensitivity, meaning how well it is able to return positive results when the virus is present, is somewhere around 60 to 70 percent.
Different companies around the world are now producing slightly different tests, so it's hard to have a precise overall figure.
But even if it were possible to increase the sensitivity to 90 percent, the magnitude of risk remains substantial as the number of people tested grows, Sampathkumar argued in a paper published in Mayo Clinic Proceedings.
"In California, estimates say the rate of COVID-19 infection may exceed 50 percent by mid-May 2020," she said.
With 40 million people, "even if only one percent of the population was tested, 20,000 false-negative results would be expected."
This makes it critical for clinicians to base their diagnosis on more than just the test: they must also examine a patient's symptoms, their potential exposure history, imaging and other lab work.
Timing is everything
Part of the problem lies in locating the virus as its area of highest concentration shifts within the body.
The main nasal swab tests examine the nasopharynx, where the back of the nose meets the top of the throat. This requires a trained hand to perform and some portion of the false negatives arises from improper procedure.
But even if done correctly, the swab may produce a false negative. That's because as the disease progresses, the virus passes from the upper to the lower respiratory system.
In these cases, the patient may be asked to try to cough up sputum -- mucus from the lower lungs -- or doctors may need to take a sample more invasively, when a patient is under sedation.
Daniel Brenner, an emergency physician at Johns Hopkins Hospital in Baltimore, described to AFP taking a test after performing a procedure called a bronchoalveolar lavage.
This was done on a patient whose nasal swab returned negative three times, but who showed all the signs of COVID-19.
Eventually, the patient's medical team placed a camera down his windpipe to examine the lungs, then sprayed fluid in and sucked out the secretions, which were then tested, resulting in a positive.
No perfect test
Uncertainty in clinical diagnoses is not new, and clinicians are well aware that no type of test for any condition can be considered perfect.
What makes COVID-19 different is its newness, said Sampathkumar.
"Most of the time when you have tests, you have test characteristics outlined carefully and warnings about tests interpretation," she said.
"We had no test for so long, and when we got the test, we started using it widely and sort of forgot the basics."
After being slow to start mass testing, the US has ramped up production and has tested almost 2.5 million people, with pharmacists now authorized to carry out the procedure.
But "the real fear of that is people who are given a false negative test and then decide that they're safe to go around their daily life and go out and expose people," said Brenner.
Much hope is placed on newly available serological tests which look for antibodies produced by a person's body in response to the virus and can tell whether a person was infected, long after they recovered.
They could also be used to help diagnose a person who is currently infected but whose PCR test results showed a false negative, by waiting a week or so for the body to produce its immune response.
"We are excited about the serologic test, but we don't know how well it will work and we are starting to study it," said Sampathkumar.
If it's about accumulating some punya..let me not lag behind...
What I am sharing here I had been doing it for some time but just recently I was able to decode it.
This is for the benefit of hardcore system backtesters who swear by it in system selection and those system hoppers who are always in search of the next holy grail system. I hope this will help enlighten some and help me gaining some punya..
Here it goes, you have found 5 different types of systems and their 10yrs bactest returns are as follows:
1. CAGR: 32%, Max DD: -40%
2. CAGR: 8%, Max DD: -18%
3. CAGR: 46%, Max DD: -76%
4. CAGR: -12%, Max DD: -36%
5. CAGR: 40%, Max DD: -62%
Rest of the parameters like R:R, Win rate, recovery factor etc are all in acceptable levels...and can be ignored.
Now the question is as a trader or investors which system would you use and why?
Get this right and I can easily say that your are ahead of 95% of traders/investors out there...
Something to keep your brains busy ... enjoy your weekend..
What I am sharing here I had been doing it for some time but just recently I was able to decode it.This is for the benefit of hardcore system backtesters who swear by it in system selection and those system hoppers who are always in search of the next holy grail system. I hope this will help enlighten some and help me gaining some punya..
Here it goes, you have found 5 different types of systems and their 10yrs bactest returns are as follows:
1. CAGR: 32%, Max DD: -40%
2. CAGR: 8%, Max DD: -18%
3. CAGR: 46%, Max DD: -76%
4. CAGR: -12%, Max DD: -36%
5. CAGR: 40%, Max DD: -62%
Rest of the parameters like R:R, Win rate, recovery factor etc are all in acceptable levels...and can be ignored.
Now the question is as a trader or investors which system would you use and why?
Get this right and I can easily say that your are ahead of 95% of traders/investors out there...
Something to keep your brains busy ... enjoy your weekend..
Ok so the answer is.. "Each of these systems are equally good and useful"!!!...
So if what I say is true then just imagine how it will change your earlier perspective on selecting your system based on backtest results or searching for new systems based on their high performance..I am saying even system 4 which gave a CAGR of -12% is good..
Now don't start throwing rotten eggs and tomatoes at me for saying this...but what I am saying is 100% true and I know what I am saying..and I am not high..
To end the suspense...the reasoning is that the systems or its performance is not important..it's how we manage the strategy is key. Every strategy has value it's just that we need to know how to use it and when.
To make it more clear, if you ask me how I will manage it?...I just have to have a portfolio view and split my capital equally among these 5 strategies and rebalance them monthly/quarterly..
Want to know what will be performance result of this portfolio? You will be surprised to know that it will give a CAGR of 53% and max DD of just 26%...
Difficult to believe right??? This is the real secret...anayze how you can use this knowledge in your trading...get it right and you will decode the market behaviour...
Enjoy and just add some punya points into my account...
To make it more clear, if you ask me how I will manage it?...I just have to have a portfolio view and split my capital equally among these 5 strategies and rebalance them monthly/quarterly..
Want to know what will be performance result of this portfolio? You will be surprised to know that it will give a CAGR of 53% and max DD of just 26%...
Difficult to believe right??? This is the real secret...anayze how you can use this knowledge in your trading...get it right and you will decode the market behaviour...
Enjoy and just add some punya points into my account...
Last edited:
@ncube
Another experienced system trader trading in US also says similar (in different forum) in that his systems combined do better than individual. Not sure if he trades them all from a single capital pool or via rebalancing.
Does keeping capital separate with periodic rebalancing test out better for you vs using single capital and different risk per trade for each system? If you use different brokers for each strategy then ofc rebalancing would be easier to implement.
I dont have experience of combining systems yet as i am just scaling up with couple of intraday ones. But will need to check once i have multiple systems.
One possible risk with the DD numbers is that number of DD events itself is not that much so how they work in combination would be a small sample and probably not as reliable, esp for HTF data. I would probably prefer to reduce size - 13% DD has more room for things to go bad vs 26%.
Another experienced system trader trading in US also says similar (in different forum) in that his systems combined do better than individual. Not sure if he trades them all from a single capital pool or via rebalancing.
Does keeping capital separate with periodic rebalancing test out better for you vs using single capital and different risk per trade for each system? If you use different brokers for each strategy then ofc rebalancing would be easier to implement.
I dont have experience of combining systems yet as i am just scaling up with couple of intraday ones. But will need to check once i have multiple systems.
One possible risk with the DD numbers is that number of DD events itself is not that much so how they work in combination would be a small sample and probably not as reliable, esp for HTF data. I would probably prefer to reduce size - 13% DD has more room for things to go bad vs 26%.
1. Risk per trade is specific to strategy right. Rebalance is done at strategy level..i.e say I have 1L then each strategy will be allocated 20K.
2. It is also important that the strategies correlation are as low as possible..so the the DD curve will be better..for example a breakout strategy combined with a mean reversion strategy will improve the overall performance.
3. How does it matter the strategies are run at one broker or multiple brokers...the strategy is managed at our end and broker platform is used just for strategy execution...the MM/ risk etc is handled outside the broker platform.
4. How much DD one is comfortable is based on the asset allocation...this happens at a level above...where you decide on how much you allocate for equity and howmuch for debt and how much of leverage you want to use.
2. It is also important that the strategies correlation are as low as possible..so the the DD curve will be better..for example a breakout strategy combined with a mean reversion strategy will improve the overall performance.
3. How does it matter the strategies are run at one broker or multiple brokers...the strategy is managed at our end and broker platform is used just for strategy execution...the MM/ risk etc is handled outside the broker platform.
4. How much DD one is comfortable is based on the asset allocation...this happens at a level above...where you decide on how much you allocate for equity and howmuch for debt and how much of leverage you want to use.
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