How to calculate the chance of encountering an alien spaceship

The US Army has released secret photos and movies. I've heard that a friend of a friend has given up on the 1% chance the UFO is alien. So far it is believed that there is 50%, does he have a reason?

People tend to see things in the สล็อต sky that they don't understand. Most of them are planes, satellites, weather balloons, clouds, rocket launches, aurora, reflections, and so on. no known explanation The problem is that people jump to the "unknown=alien" conclusion and when you think about it. It's quite strange Why not an angel?

However, I prefer doing math instead of the Bayes formula (below), which is the core of statistics. to give the probability (Pr) of something, with some evidence
Spell it out saying that the probability that the UFO is an alien receiving some evidence is equal to the probability that the evidence will show up if the UFO is actually an alien multiplied

by the likelihood that it has. alien which need to be divided according to the possibility of actual evidence which is difficult to find a solution But what we really care about is if evidence tells us we should believe in aliens. compared to not believing in aliens We can do this by dividing the above equation by a pair of non-alien UFOs:
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