Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Not worth keeping

I bought the book because it's required for my statistics I class.I found it lacking both breadth and depth. When a concept is confusing, there was no explanation (sometimes, the definition to the concept is confusing); there were formulas presented for a situation but not much explanation as to why. And when there was a topic there seem to be interesting, there was just a blurb and no more insights and references. I don't think it's worth keeping.