Testing for anchoring bias regarding a quantity you were fairly certain about wouldn't yield significant results. Of course, you do have some idea--if I asked you whether the population of the Central African Republic were more or less than 7 billion people, you could confidently answer "lower."

So, like me, you had a probability distribution regarding the answer, but it was diffuse enough that the "20 million" anchor moved it upward. At least, that seems to be the case.

Congratulations on the original research, Prase!