The main issue in averaging scores consists in comparing the existing different rating systems (there is unfortunately no ISO norm governing this delicate subject for the moment!). Basically, there are two different approaches in the notation of wines: the American approach which is extremely precise, often based on a scholar evaluation scale base of 100 points, which allows a more subtle differentiation of wine-tasting. The European approach is more adaptable, the objective of which is to communicate a general impression of the wine in comparison to a precise expertise of the product. A wine noted 86.5 is it really much better than it’s cousin at 85? It is a question of flavors and colors…   
To simplify our calculation approach, we have decided to adopt the American approach, so as to proceed in a more efficient manner in different comparative calculations. The European scales are consequently transposed to a scale of 100 points i.e. a wine rated with a 4 stars value will be transposed in our study in a bracket of notation of between 90 and 92 points, thus we have systematically adopted in our data a mean value of 91 points. The concern in knowing why the wine-taster, after having rated a wine at 4 stars, would have chosen 90 instead of 92 points remains a mystery deeply anchored in the thoughts of the expert. 

It must be noted however that Contributors who have the habit of noting their wines on a scale of 20 points, show a tendency to assign more easily a lower rating in comparison to wine-tasters using other grading systems, more particularly for wines that are rated disappointing. Consequently, when using a rating system on 20 points, it is not rare to find notations of 12/20 which transposes to a 60/100 rating, despite the fact that wine-tasters using the 100 point scale would rarely have the occasion to evaluate wines under a value of 70/100, this value representing the extreme lower limit in acceptable quality criteria.

ccvo-bg's approach

The table of scores is established by using the mathematical average of the results of all the Contributors. However, you should avoid falling in certain traps when reading the table. Take for example two wines with an average rating of 85/100.