I disagree completely however they are basing this on some sort of formula. I believe the review process is not bias if the right person is making the review. For example, I am very honest with my reviews, regardless if I have been incentivised by receiving something for free or at a discount. Firstly I wouldn't even be reviewing it if I didn't get the product in the first place and secondly, I want my review to be as honest as possible, just like I count on the ones that I read. I believe each person that purchases stuff on Amazon, that has read the many reviews on the product they are about to buy and then make their own reviews based on this. If anything I will say that I do sort my search by buyers "average Customer review" but then utilize the statistics when I make my own. I have actually had some people reply to my review when I have given it a poor rating, stating I was not being fair, especially when I have said that I returned the product for whatever reason. In some cases I have updated my review and either marked it higher or lower, based on the time I have used it and if it broke or stopped functioning after a short period of time as I believe the longevity of a product is also just as important.
Why Amazon's "Incentivized" Reviews Are Biased, Even If They Claim They Aren't