Just... no. You're presenting "anecdotal" as if to contrast it with something like "established pattern." But "anecdotal" just means that something is a remembered story, nothing else.
So, there is something which we do called "observation." This is when we want to know the truth of something, so we set up some sort of meaningful experiment which we can do in the world, and find out. We go out and observe.
The reason that an anecdote is not an observation is because it comes to you first. That is, you already know the result of the anecdote before you select the data; it is something you "remember" when you hear about a new situation. This invokes all kinds of biases about how you remember, because you tend to remember anomalies -- and you tend to misremember their content. In anecdotes there is no "control group" and there isn't even a hope for a control; it's all been selected out anyway.
In this respect a single observation is not anecdotal, because they come from separate places. If a doctor puts a flow-meter in an artery after a bypass surgery to see if there is blood flowing at a normal cardiac rate, that is not an "anecdote", that is an "observation." It is not based on some sort of human reckoning; "I've done many bypass surgeries and I once saw an artery which looked just like that and was not, in fact, obstructed," but rather it's something reliable: at this time, a normal amount of blood was flowing through this artery.
