Squeeze the Balloon: When Debiasing Shifts Bias Elsewhere
Debiasing methods for recommender systems usually fix one bias at a time and are judged on accuracy alone. On the KuaiRand short-video dataset, we test three such methods against all three biases (popularity, exposure and video duration), using randomly shown videos as an unbiased test set. Like squeezing a balloon, removing one bias often pushes another up, and accuracy metrics barely notice.