Hi Nermin, It turns out that Udemy doesn't actually know how their own ratings are calculated. The information shared by the moderators above is incorrect. I don't blame them, but for sure it's incorrect. What I'm sure actually happens is that the last 10 reviews are averaged, with some extra modifications (as described by Abbie above). So if you have 20 reviews, it's an average of reviews 11-20. And if you get a 21st review, which is worse than the 11th one, then your rating will go down. Perhaps your rating is 4.47, the 11th was a 5* review from someone who watched the whole course, and the 21st is a 5* review from someone who only watched 20%. Then the course rating might drop to e.g. 4.44. Once I figured out how Udemy actually calculates ratings, the behaviour of my ratings made sense.
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