Firstly, many statistics are taken from a small group of people used to represent the general population. Say a news channel reported that 81% of teenagers in America were planning on going to a four-year college. This statistic is most likely taken from a randomly selected group of teenagers, and calculated with a margin of error. Because after all, it's nearly impossible to survey every single teenager in America. This can lead to some statistics that are not really representative of the actual percentage of people. This only gets more likely the larger the general population being "surveyed" is. Another reason is that the media is not always truthful with statistics. Things can be altered and not many people will notice. Hope this helps!