The P.T. Barnum effect refers to the tendency of people accepting misleading descriptions. The reason the P.T. Barnum effect is misleading is because it has high base rates, it can easily apply to a lot of people. The P.T. Barnum effect is important because it is widely used in popular psychology. It can lead people to believing that certain traits describe specific groups of people when they don't, it can lead to falsely accusing someone of a crime, etc... I was once prone to the P.T. Barnum effect when a palm reader was telling me about my future. She told me that I was going to have money, a house, and possibly kids. This can apply to many people, which led me to not believe it. I am still wondering if the government uses any type of strategies to accuse people such as the P.T. Barnum effect.
This video exemplifies how most of today's astrology isn't necessarily false, but not necessarily true, because of the high base rate descriptions the astrologers give to the clients.
Near the end of the video, we see that with the personality descriptions the people are given, they're very exited to receive it, and most of them claim that it describes them with high accuracy. What they didn't know, was that it described the mass murderer's horoscope, and it was matched up with their horoscopes. What can evaluate this particular claim is using occam's razor, and extra ordinary claims to evaluate this situation. We can see that their has to be an extraordinary claim for each one of the people who took the test who had the same personality traits as the mass murderer, and that there are simpler explanations to defining their personalities.
It is good to avoid such high base rates, because if we do, we'll be prone to pseudoscience, which is not a good way of evaluating things with a scientific mindset. Therefore, we can get unwanted causes such as believing we are someone who we aren't.