4 ms·

The "fallacy" described here is a non-issue. Medical tests have the same characteristics but are still incredibly useful. HIV testing is roughly 99% accurate,

by codex 13y ago

The "fallacy" described here is a non-issue. Medical tests have the same characteristics but are still incredibly useful. HIV testing is roughly 99% accurate, but given the large number of tests performed, a very large percentage of people will end up with the wrong result. And yet this test is vital. Even wildly inaccurate tests can be useful. Imagine that driving drunk will result in a accident 10% of the time. 90% of the time, however, a driver will make it home safely. This is a wildly inaccurate predictor, but it still critical to know someone's blood alcohol level before giving them their keys. One must simply be aware of the uncertainty involved in any test, and treat test results as probabilistic signal, not as proof.

michaelfeathers 13y ago
The issue is that civil rights are supposed to be immune to probabilistic signal. In practice, it won't turn out that way. Look at racial profiling.
DanBC 13y ago
I tend to agree with you, except it is not a non issue. Look at the numbers of people getting very serious medical treatment because they, and their clinicians, have not understood the numbers. If doctor (well educated intelligent person) cannot get this right I'm scared that labelling someone as "POTENTIAL TERRORIST" on the basis of a 1 in X possibility is going to have disastrous consequences.
- _delirium 13y ago
  Yes, this is an active area of debate in evidence-based medicine (EBM). If you aggregate outcomes, administering some tests actually appears to worsen prognosis, in the sense that if you take two groups of people with identical distributions of (unknown) conditions, and test one group while not testing the other, the tested group has worse overall outcomes. For example, in some cases people have surgery for a condition that, absent the test, would have remained asymptomatic and benignly ignored. With certain kinds of conditions, negative outcomes from retrospectively unnecessary treatment are frequent enough to outweigh the cases where discovery and treatment improves outcomes, if we're talking about aggregate outcomes. Of course, discovery does not require treatment, so you could test, find a positive, and not do anything. But EBM people tend to view idealized responses with suspicion, and some argue that taken in real-world conditions, not administering certain tests, or administering them in more restricted situations, or at least not recommending them as the default, would improve aggregate outcomes (and the data seems to support that). They would then restrict the tests to cases where testing statistically improves outcomes.
arbuge 13y ago
I once tested positive for HIV with the basic antibody test you mention - a pretty stunning result in view of my lifestyle. A followup Western blot test with higher accuracy confirmed I was not positive. The basic test is fast and cheap but if there are no more accurate tests to detect false positives, it's a dangerous thing to rely on. Same logic applies in other situations.
muyuu 13y ago
HIV testing is largely a fraud, though, as it's conclusions are based on unscientific claims that HIV and AIDS are the same thing or even scientifically proven correlated. The field is laughable, really. It's sad that people making important decisions in the medical and pharmaceutical fields cannot correctly interpret a confusion matrix, or if they can they are corrupt and decide to ignore it anyway. You really don't want to apply the same standards to law enforcement, as they are appalling. EDIT: to the downvoters, I'd suggest doing some reading. In particular, check on the existence of any verifiable testing that proves any semblance of correlation between HIV and AIDS. The standard is appalling for any scientist who's willing to check on the numbers. In general, the standard in medical science is rather low compared to say physics, but in this case it's astonishingly low considering the accolades Montagnier got for his research. I understand it's easy to dismiss this as conspiranoia but it really is not. There are dubious claims passed as truths with very specific interests behind. Not making an assertion either way on the HIV<->AIDS relationship, just pointing out that the standard of the research is shocking and the statistics skills of the people involved are incredibly poor, if not intentionally corrupt.
- fosap 13y ago
  This is even more pathetic than creationism. This is on par with insisting that the earth is flat. Denial is a hell of a drug. Using condoms ever killed anybody. Stay save. And if you personally refuse therapy, ok. But HIV does cause AIDS and has a one hundred percent lethality. In case you affected use the remaining time.
  - muyuu 13y ago
    You are making a series of stupid assumptions here. Like I'm denying that AIDS kills, or that STDs kill. It's clearly established. Which is why I've always been extremely cautious and I'm healthy as it gets. The fact that AIDS is virus-induced, that remains unproven. However, it's pandered as such and a number of companies are cashing big on antivirals and antiretrovirals, in many cases worsening the patient's health. To claim something is proven without proof, that is pathetic. And this is not the only scam induced by big pharma. There are many other perverse effects stemming directly from the fact that pharmaceuticals cash big on chronic illnesses, giving them an incentive to research not in cures, but in long lasting treatments. Feel free to downvote away though. It's important and downvotes might actually get more people to read it.

by codex 13y ago

michaelfeathers 13y ago

The issue is that civil rights are supposed to be immune to probabilistic signal. In practice, it won't turn out that way. Look at racial profiling.

DanBC 13y ago

I tend to agree with you, except it is not a non issue. Look at the numbers of people getting very serious medical treatment because they, and their clinicians, have not understood the numbers. If doctor (well educated intelligent person) cannot get this right I'm scared that labelling someone as "POTENTIAL TERRORIST" on the basis of a 1 in X possibility is going to have disastrous consequences.

_delirium 13y ago
Yes, this is an active area of debate in evidence-based medicine (EBM). If you aggregate outcomes, administering some tests actually appears to worsen prognosis, in the sense that if you take two groups of people with identical distributions of (unknown) conditions, and test one group while not testing the other, the tested group has worse overall outcomes. For example, in some cases people have surgery for a condition that, absent the test, would have remained asymptomatic and benignly ignored. With certain kinds of conditions, negative outcomes from retrospectively unnecessary treatment are frequent enough to outweigh the cases where discovery and treatment improves outcomes, if we're talking about aggregate outcomes. Of course, discovery does not require treatment, so you could test, find a positive, and not do anything. But EBM people tend to view idealized responses with suspicion, and some argue that taken in real-world conditions, not administering certain tests, or administering them in more restricted situations, or at least not recommending them as the default, would improve aggregate outcomes (and the data seems to support that). They would then restrict the tests to cases where testing statistically improves outcomes.

arbuge 13y ago

I once tested positive for HIV with the basic antibody test you mention - a pretty stunning result in view of my lifestyle. A followup Western blot test with higher accuracy confirmed I was not positive. The basic test is fast and cheap but if there are no more accurate tests to detect false positives, it's a dangerous thing to rely on. Same logic applies in other situations.

muyuu 13y ago

HIV testing is largely a fraud, though, as it's conclusions are based on unscientific claims that HIV and AIDS are the same thing or even scientifically proven correlated. The field is laughable, really. It's sad that people making important decisions in the medical and pharmaceutical fields cannot correctly interpret a confusion matrix, or if they can they are corrupt and decide to ignore it anyway. You really don't want to apply the same standards to law enforcement, as they are appalling. EDIT: to the downvoters, I'd suggest doing some reading. In particular, check on the existence of any verifiable testing that proves any semblance of correlation between HIV and AIDS. The standard is appalling for any scientist who's willing to check on the numbers. In general, the standard in medical science is rather low compared to say physics, but in this case it's astonishingly low considering the accolades Montagnier got for his research. I understand it's easy to dismiss this as conspiranoia but it really is not. There are dubious claims passed as truths with very specific interests behind. Not making an assertion either way on the HIV<->AIDS relationship, just pointing out that the standard of the research is shocking and the statistics skills of the people involved are incredibly poor, if not intentionally corrupt.

fosap 13y ago
This is even more pathetic than creationism. This is on par with insisting that the earth is flat. Denial is a hell of a drug. Using condoms ever killed anybody. Stay save. And if you personally refuse therapy, ok. But HIV does cause AIDS and has a one hundred percent lethality. In case you affected use the remaining time.
- muyuu 13y ago
  You are making a series of stupid assumptions here. Like I'm denying that AIDS kills, or that STDs kill. It's clearly established. Which is why I've always been extremely cautious and I'm healthy as it gets. The fact that AIDS is virus-induced, that remains unproven. However, it's pandered as such and a number of companies are cashing big on antivirals and antiretrovirals, in many cases worsening the patient's health. To claim something is proven without proof, that is pathetic. And this is not the only scam induced by big pharma. There are many other perverse effects stemming directly from the fact that pharmaceuticals cash big on chronic illnesses, giving them an incentive to research not in cures, but in long lasting treatments. Feel free to downvote away though. It's important and downvotes might actually get more people to read it.