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What does the color of the Gallery Stats boxes mean?
The color of the GalleryStats boxes for each individual deviation is determined by analyzing the ratio of the comments and the favourites of the deviation. The more favourites to comments ratio a deviation has, the darker orange it will be. The less favourites to comments ratio, the whiter it will be. Once a deviation surpasses the ratio of 1 to 1 for favourites to comments, it will stay a dark orange and wont get any darker.
So GalleryStats prioritizes favourites as an indication of a great work. The reason for this is that any deviation can get lots of comments, both from people just saying they don't like it to the owner of the deviation just "chatting" or thanking a commenter. So comments would not be a good way to tell how good a deviation is doing.
Favourites however, are a good indicator of how well a deviation is received by other deviants. So if you analyze the number of favourites to comments ratio, you get a good idea of how well a deviation is faring. For example, a deviation which received 100 comments but only 10 favourites, didn't do as well as a deviation which received 20 comments and 5 favourites, meaning that less people saw it but more of those people added it to their favs as compared to the deviation with 100 comments and only 10 favourites. Thus the reason for using a ratio.