  A common form of competition is one where judges grade contestants'
performances which are then compiled to determine the final ranking of the
contestants. Unlike in another common form of competition where two contestants
play a head-to-head match to produce a winner as in football or basketball, the
objectivity of judges are prone to be questioned, potentially undermining the
public's trust in the fairness of the competition. In this work we show, by
modeling the judge--contestant competition as a weighted bipartite network, how
we can identify biased scores and measure their impact on our inference of the
network structure. Analyzing the prestigious International Chopin Piano
Competition of 2015 with a well-publicized scoring controversy as an example,
we show that even a single statistically uncharacteristic score can be enough
to gravely distort our inference of the community structure, demonstrating the
importance of detecting and eliminating biases. In the process we also find
that there does not exist a significant system-wide bias of the judges based on
the the race of the contestants.
