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Drug testing is a good example for most people to understand why Bayesian thinking is relevant. https://www.mun.ca/biology/scarr/4250_Bayes_Theorem.html https:

Drug testing is a good example for most people to understand why Bayesian thinking is relevant. https://www.mun.ca/biology/scarr/4250_Bayes_Theorem.html https://www.mun.ca/biology/scarr/4250_Bayes_Theorem.html Imagine that a driver gets hit by accident. He's tested as part of company policy, and tests positive. He gets fired, even though the test only really tells us there's a 33.2% chance he was actually using the drug. Real world drug tests are a lot worse than 1% false positive and false negative rate. Every time someone gets fired for a positive test, or loses custody of their kid, or so on, it reinforces whatever statistics are being collected as if the test were a ground truth. They're hardly ever questioned, and there's usually no recourse without an expensive legal fight. The false positive rate for drug dogs is higher than 40%, for contrast. When a dog "alerts" its worse than a flip of a coin. All that matters is if an officer feels like fucking up your day. Testing used in situations that are legally significant in people's lives should be required to reach a statistically valid threshold of accuracy, like 99.999% of the times this process is performed, it matches reality. A high sensitivity and high specificity aren't enough, but they're framed as highly accurate and reliable by often well intentioned people who simply aren't thinking in a Bayesian way.

moralestapia 5y ago
>All that matters is if an officer feels like fucking up your day. This is what most people don't seem to get. Devices like the ADE 651 or the GT200 were bought by the thousands by law enforcement agencies worldwide, not because they were stupid, but instead, so they could have another "data point" against you that they can use at their discretion. "Sorry, this dot blinked three times so I'm gonna have to detain you: It's standard procedure, I'm only doing my job."
- zerocrates 5y ago
  What's relevant isn't whether a technology or forensic discipline is good, just whether courts will accept it. Antonin Scalia (in)famously commented in one of the Supreme Court's dog-sniff 4th Amendment cases that obviously the police would want dogs that didn't produce false positive alerts, since they wouldn't want to waste their time searching where there were no drugs. The resulting caselaw sets up a situation where a dog can be wrong over half the time and still be used. The concept that "probable cause on four legs" would be used simply in order to get to search where they otherwise couldn't was apparently unthinkable.
  - robbedpeter 5y ago
    Just like McConnell and anti corruption legislation. Nobody in the senate was corrupt, so why in the world would they need rules against corruption? The flawless logic of our leaders is astonishing.
PaulHoule 5y ago
Animals are great at reading people emotionally. Given that the handler has some subjectivity odds are pretty good the handler perceives the dog alerts if the cops are themselves suspicious.

moralestapia 5y ago

>All that matters is if an officer feels like fucking up your day. This is what most people don't seem to get. Devices like the ADE 651 or the GT200 were bought by the thousands by law enforcement agencies worldwide, not because they were stupid, but instead, so they could have another "data point" against you that they can use at their discretion. "Sorry, this dot blinked three times so I'm gonna have to detain you: It's standard procedure, I'm only doing my job."

zerocrates 5y ago
What's relevant isn't whether a technology or forensic discipline is good, just whether courts will accept it. Antonin Scalia (in)famously commented in one of the Supreme Court's dog-sniff 4th Amendment cases that obviously the police would want dogs that didn't produce false positive alerts, since they wouldn't want to waste their time searching where there were no drugs. The resulting caselaw sets up a situation where a dog can be wrong over half the time and still be used. The concept that "probable cause on four legs" would be used simply in order to get to search where they otherwise couldn't was apparently unthinkable.
- robbedpeter 5y ago
  Just like McConnell and anti corruption legislation. Nobody in the senate was corrupt, so why in the world would they need rules against corruption? The flawless logic of our leaders is astonishing.

PaulHoule 5y ago

Animals are great at reading people emotionally. Given that the handler has some subjectivity odds are pretty good the handler perceives the dog alerts if the cops are themselves suspicious.