Knowledge
Review corpus
A review corpus is the set of all statements about a venue on which the analysis runs, split into those with text and those that are a bare rating.
Where it comes from
Corpus size decides whether anything can be concluded from the numbers. Only the count of reviews WITH TEXT matters, because a bare star yields neither a category nor a cause. A business saying "I have four hundred reviews" usually has about two hundred that anything follows from.
What it means in practice
Practical thresholds: below twenty reviews with text on a topic, read them one by one and count nothing; from twenty to two hundred you can speak about repetition; above two hundred seasonality and period comparison start working too.