Essentially the difference between the two is how systematic the gathering of information is. A juicy urban legend gets passed around and repeated with small variations all other place: hearing it ten times is uninformative. TripAdivsor gathers reviews in a more systematic way, so is better. If people started sending each other the snarkiest reviews they saw on TripAdvisor, this would degenerate more into anecdotes again.
The question is always, are you getting a reasonable sample of the anecdotes out there.
It depends on how independent the anecdotes are.
I wouldn’t agree that 100 reviews on TripAdvisor for a hotel should weigh little more than 10 reviews.
That approaches data more.
Essentially the difference between the two is how systematic the gathering of information is. A juicy urban legend gets passed around and repeated with small variations all other place: hearing it ten times is uninformative. TripAdivsor gathers reviews in a more systematic way, so is better. If people started sending each other the snarkiest reviews they saw on TripAdvisor, this would degenerate more into anecdotes again.
The question is always, are you getting a reasonable sample of the anecdotes out there.
The plural of anecdote is qualitative study.