To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
The books in this series are really good. I like the simplicity, repetition and the fact that the book tells you what not to do AND what to do instead. The pictures and colors are beautiful. They make the point with our 18 month old guy.