Anthropic Bias explores how to reason when you suspect that your evidence is biased by 'observation selection effects'--that is, evidence that has been filtered by the precondition that there be some suitably positioned observer to 'have' the evidence. This conundrum--sometimes alluded to as 'the anthropic principle,' 'self-locating belief,' or 'indexical information'--turns out to be a surprisingly perplexing and intellectually stimulating challenge, one abounding with important implications for many areas in science and philosophy. There are the philosophical thought experiments and paradoxes: the Doomsday Argument; Sleeping Beauty; the Presumptuous Philosopher; Adam & Eve; the Absent-Minded Driver; the Shooting Room. And there are the applications in contemporary science: cosmology ('How many universes are there?', 'Why does the universe appear fine-tuned for life?'); evolutionary theory ('How improbable was the evolution of intelligent life on our planet?'); the problem of time's