Using Twitter to Learn about the Autism Community 33 misclassified tweets indeed were not related to ASD. Rather the term “adhd” was used as a hyperbole for an inattentive or easily distracted person. Here are a few examples: We made a similar observation with regard to the usage of the word “aspie” which too is used loosely in colloquial speech (albeit with a lower frequency than “adhd”). This explains the performance of the classifier trained on data matched by the other three keywords and eval- uated on the tweets matched by “aspie” only, which was also worse than the corresponding performance in the experiments in which the left out keyword was “autism” or “asperger” but not as much as when “adhd” was left out. In summary, this experiment offers several important insights useful in the practical application of the ideas presented in the present paper. Firstly, it showed that the choice of keywords does not need to be a complex process in the sense that a small number of keywords is sufficient to learn the relevant salient characteristics of a theme associated with them. Additional keywords appear to be redundant, adding no new information and not resulting in improved performance. Secondly, the experiment demonstrated how potentially bad keyword choices can be automatically detected and therefore removed. This can be done either fully automatically or in a semi-automatic fashion following human input (approval). The aim of this work was to investigate the potential of data-mining messages posted on Twitter to learn about the concerns, practices, and more generally topics of conversation of people interested in the autism spectrum disorder. We approached this problem first by harvesting a large data set of tweets each of which we designated as belonging either to the ASD-related subset of the data corpus or the control subset. Using this data set we con- ducted a series of experiments which analysed both common and differential characteristics 5 Summary and conclusions – Watching football is such a commitment. I’m too adhd for this. – I think we both have adhd – I feel like I have adhd.. I cannot write 300 words and not stop for a “break” – And then your adhd causes you to forget everything as soon as you get on your phone