This document discusses techniques for mining online reviews to forecast product sales performance. It focuses on analyzing movie reviews to predict box office revenues. Sentiment PLSA is used to identify hidden sentiment factors in reviews by categorizing words as positive or negative. The ARSA model then predicts sales based on review sentiment. Clustering and classification algorithms are also proposed for sentiment analysis. Accurately predicting sales based on textual reviews, beyond just star ratings, can provide valuable business intelligence for firms.