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.
If you want to learn about facial expressions, this is the book you want. From the works of Dr Paul Ekman its amazing how you can learn all about how your face can give you away. If like me you enjoyed the TV series Lie To Me, then you need to read this book.