What is sentiment analysis?
Sentiment analysis
Automatic classification of a mention as positive, negative, or neutral, used to summarise the tone of a large volume of posts.
Sentiment is most useful in aggregate and least useful per post. Sarcasm, in-jokes, and category slang defeat classifiers routinely, so a single post's label should never be trusted, while the direction of a few thousand labels usually is.
Treat a sudden swing as a prompt to read the posts, not as a finding in itself.