In our interdisciplinary, collaborative research, we have found that humanities and social science researchers would like to analyze data underlying LLMs as well as study how language tools (e.g., emotion detection) work on their data. Existing tools are often unintuitive for such researchers and do not provide them enough agency. In this paper, we introduce CorpusLens, an LLM-based tool to aid social, humanistic, and language science researchers in exploratory textual data analysis. We present the design of CorpusLens as well as a user study showing that researchers found CorpusLens to be more helpful than prior tools they had used, while also rating it as intuitive, easy to use, transparent and enabling.

With a combination of quantitative experiments, human judgments, and qualitative analyses, we evaluate the quantity and quality of African American Language (AAL) representation in 12 predominantly English, open-source pretraining corpora. We specifically focus on the sources, variation, and naturalness of included AAL texts representing the AAL speaking community. We find that AAL is underrepresented in all evaluated pretraining corpora compared to US demographics, constituting as few as 0.007% and at most 0.18% of documents. We also find that more than 25% of AAL texts in C4 may be perceived as inappropriate for LLMs to generate and to reinforce harmful stereotypes. Finally, we find that most automated filters are more likely to conserve White Mainstream English (WME) texts over AAL in pretraining corpora.