Unforunately I slightly disagree UN. Only one (or a select of a specific group) person's observation of something happening just once or twice definately is not the same as a scientist who has complete control of the situtation and factors. However, repeated patterns that are noticed over and over and over again by thousands of people over many, many years, chances are then the "casual observation" and scientific ones are just about the same.
also, when you say that it depends on perspective, you also need to consider the flip side of a regular person without the complete education of a person say like a scientist then he or she is will probably want to consider him or herself as equal in knowledge as the 'high and mighty' person as to not feel inferior. so he or she will naturally lean towards saying that his or her facts are the same as a 'high and mighty' person.
JettaJokey: I"m not meaning to stir things up, but techinically couldn't we compare ourselves to yahooanswer people? There are a good number of us who have no official education and or training in the field of fish keeping (I highly doubt every single person online here has majored in a field like marine biology and such). Most of us have learned from experience over the years (aka 'casual observations') and from what we've heard from other people. Yet people come here, seeking answers and help and to share experiences, and I think you'll admit that our 'casual observations' over the years have gotten pretty gosh darn accurate (for the most part). Chances are if someone came looking for an answer to why his fish is sick and how to heal it, we could give just as accurate of information as could someone trained in the field.