text: how do those fortune telling/horoscope email chain letters work? they're sometimes seemingly accurate.? occasionally i get emails asking to answer a number of questions in exchange for making some kind of prediction or assessment on your life.  ex: what's your favorite number, think of a favorite song title, what's the first image that comes into your mind when you read the world "blue", etc.  sometimes i'll answer these for fun and then be surprised by the seemingly accurate results regarding my feelings or ideas of my own future.  can anybody explain the logic that goes into designing such a questionnaire that could somehow be accurate to such a potentially wide audience. i'm not sure exactly which ones you are referring to, but i have come across quite a few in my time.  some can merely be numbers based, for example they may get you to pick a number, multiply it by something else, add or subtract another number etc... then with your final number they can saposedly read your mind, but really the mathematical formula leads everyone to the same number.  the other ones are more psychological and statistical, working on the most likely answers a wide range of people will come up with. they will also lead you to the answer they want through what information they give you (visual/words), like advertising.