Content analysis
Content analysis extracts the key themes of large bodies of online documents, derived from the presence of certain words or concepts within texts or sets of texts. Collecting information from these bodies of text is a form of data mining. The tools needed for content analysis operate at two levels: the tools needed to find the content, and the tools needed to analyse the content. The methods are a mixture of linguistics and statistics, and there are free tools available as well as commercial ones. To conduct a content analysis text is coded and categorised on a variety of levels: word, word sense, phrase, sentence, or theme. Relational analysis (or semantic analysis) can explore the connections between concepts or themes or categories. Conceptual analysis quantifies or counts the presence of a concept or category.
See the Iowa State University Library research method guide to content analysis https://instr.iastate.libguides.com/c.php?g=49332&p=318069