Tagging Performance Correlates with Author Age

Many NLP tools for English and German are based on manually annotated articles from the Wall Street Journal and Frankfurter Rundschau. The average readers of these two newspapers are middle-aged (55 and 47 years old, respectively), and the annotated articles are more than 20 years old by now. This leads us to speculate whether tools induced from these resources (such as part-of-speech taggers) put older language users at an advantage. We show that this is actually the case in both languages, and that the cause goes beyond simple vocabulary differences. In our experiments, we control for gender and region.