Abstract: For the problem that the recommendation system is vulnerable to the impact of Spammer attack, which leads to the inaccuracy of the final item rating, this paper proposes a user reputation ranking algorithm based on median. The algorithm readjusts the weight of user’s rating by measuring user’s reputation. On the other hand, according to the median, it has the property of less susceptible to the effects of extreme rating, the algorithm selects the median from the distances between user rank and object rank as the criterion to decrease user reputation, then iterates until convergence to adjust the user reputation and final rating. Operation result of multiple real data sets shows that the algorithm obtains a more reasonable reputation distribution and a higher accuracy, and after preprocessing by this algorithm, the rating data can get a better Root Mean Square Error(RMSE) value on SVD++.
Root Mean Square Error(RMSE)