Why win/loss ratio can’t be used as a proxy for ImageScore

A lot of members have asked some variation the question “why is my win loss ratio the same as this other images but my ImageScore is much lower.”  I can understand the confusion that this might cause and we have debated extensively whether to even show the wins and losses of an image.  Ultimately we’ve decided to show it (because it is interesting information) but not to emphasize it (because it does not correlate directly to score).

The simple answer to all of these types of questions is that it is not the ratio of wins or losses that matter in generating ImageScore – it is the PATTERN of those wins and losses.

Here is an a dramatic illustration of why:

Image#1 (a not very good image) looses it’s first 10 duels and its ImageScore rises quickly at first (because the built-in new image handicap is being burned down) then settles down to an ImageScore of 350. Now the ImageDuel system makes sure it is played against some of the worst images on the site and it wins 66% of its duels against these relatively poor images.  Because the win/loss ratio against this group of images is 20/10 it means that the system overshot this image’s score on the down side (because of the 10 immediate losses) and has to bring it back up a little to find the right group of images to play against.  But note here that even though this image is playing against some of the worst images on the site it is still loosing 1/3 of the time so its ImageScore doesn’t move up very much.  In this case the image ends up with an ImageScore of 400 and with a win/loss ratio of 20/20 (i.e. first 10 losses and then a 2/1 win loss ratio after that)

Image#2 (an amazing image) wins first 10 duels and ends up with an image score of 600 after 10 duels. Now it’s playing against some of the best images on the site so it begins to loose 2/3rds of the time.   This image is still winning against amazing images so its image score stays constant (as the new image handicap burns off) and dnds up with an ImageScore of 600 and a win/loss ratio of 20/20.

So you see the pattern of duels is INCREDIBLY important in terms of finding ImageScore.

Here is another example:

These two images will have drastically different ImageScores:

The first one will be MUCH higher.

Confusing I know – but if it was simple to create an algorithm that works as well as Pixoto’s people would have done it long ago.


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