To test whether authorship of novels influences our results we removed the author signal by allowing only one document per author. In this way, we construct a new dataset called ‘uni’. The sampling is done once so that the same novels are used in each setting. As shown in figure 4, we observe a much lower quality after removing the authorship information indicating an overemphasized focus of features and models on the hidden authorship signal. This varies for different settings as adventure/educational shows a loss of 0.09 (blue lines) and educational/social loses 0.23 (red lines). The relatively small loss in the first setting is remarkable as it contains 8 novels per author on average. One would expect the opposite given the weaker author signal of two novels per author for the other categories.