Persistence in Recommender Systems: Giving the Same Recommendations to the Same Users Multiple Times

How do click-through rates vary between research paper recommendations previously shown to the same users and recommendations shown for the very first time? To answer this question we analyzed 31,942 research paper recommendations given to 1,155 students and researchers with the literature management software Docear. Results indicate that recommendations should only be given once. Click-through rates for ‘fresh’, i.e. previously unknown, recommendations are twice as high as for already known recommendations. Results also show that some users are ‘oblivious’. It frequently happened that users clicked on recommendations they already knew. In one case the same recommendation was shown six times to the same user and the user clicked on it each time again. Overall, around 50% of clicks on reshown recommendations were such ‘oblivious-clicks’.