you have some prior information that is not present yet or reflected yet in this data data is too small you have knowledge about the world that you've condensed in this notion that actually sometimes it could fall the other way just hasn't happened yet in this experiment so we can do you can introduce a prior explicitly to account for that you can say well my prior is something that some probability on theta some 1 1 minus theta I raise them to the same power here theta times 1 minus theta it's as if as if I've seen one