概率：一条真鱼
Probability: the one true fish
我即将参加机器学习考试，我需要帮助来回答这个问题。
There are a million identical fish in a lake, one of which has
swallowed the One True Ring. You must get it back! After months of
effort, you catch another random fish and pass your metal detector
over it, and the detector beeps! It is the best metal detector money
can buy, and has a very low error rate: it fails to beep when near the
ring only one in a billion times, and it beeps incorrectly only one in
ten thousand times. What is the probability that, at long last, you’ve
found your precious ring?
这是我得出的答案：
这是解决这类问题的正确方法吗？这在一定程度上是正确的答案吗？
你想要的是在探测器发出哔哔声的情况下钓到正确鱼的概率，即 P(A|B)。
P(B|A) = 9999/10000 是在您钓到正确鱼的情况下探测器发出哔哔声的概率。但是，我们不知道您的鱼是否正确。您所知道的只是检测器发出哔哔声，您无法判断它是概率为 P(B|A) 的真阳性还是概率为 P(B|not A).
的假阳性
贝叶斯定理可让您在 P(B|A) 和 P(A|B) 之间切换，因此其他信息并非毫无用处。你确实需要这一切来解决问题。
我即将参加机器学习考试，我需要帮助来回答这个问题。
There are a million identical fish in a lake, one of which has swallowed the One True Ring. You must get it back! After months of effort, you catch another random fish and pass your metal detector over it, and the detector beeps! It is the best metal detector money can buy, and has a very low error rate: it fails to beep when near the ring only one in a billion times, and it beeps incorrectly only one in ten thousand times. What is the probability that, at long last, you’ve found your precious ring?
这是我得出的答案：
这是解决这类问题的正确方法吗？这在一定程度上是正确的答案吗？
你想要的是在探测器发出哔哔声的情况下钓到正确鱼的概率，即 P(A|B)。
P(B|A) = 9999/10000 是在您钓到正确鱼的情况下探测器发出哔哔声的概率。但是，我们不知道您的鱼是否正确。您所知道的只是检测器发出哔哔声，您无法判断它是概率为 P(B|A) 的真阳性还是概率为 P(B|not A).
贝叶斯定理可让您在 P(B|A) 和 P(A|B) 之间切换，因此其他信息并非毫无用处。你确实需要这一切来解决问题。