What's biased is assuming two things are related without good rationale. The scientific principle is called the Null Hypothesis: it means two things are assumed to not be related until there's good reason to suggest they are. A very good point. And one that works in your favour. You want to lump multiple monster sightings in to one? OK, I'll go find some reports of sea monster sightings that have been admitted to be false - hoaxes. Great, now your account is shoulder-to-shoulder with known hoaxes. Glad we lumped them all together? Can I now conclude that yours is likewise false? No, it's better for you if we examine it without lumping in with others, don't you agree? Yes, that is science. Two isolated unexplained incidents must be analyzed on their own merits. It is only once we find a common cause that we can start to look at them together. To link them prematurely is to form a hasty conclusion- and that biases your examination.
