chalk talk vs doctoral thesis

chalk talk

noun
  • An informal lecture on an academic subject. 

  • A music hall act in which a performer makes chalk caricatures whilst reciting a monologue 

doctoral thesis

noun
  • A research paper that a student writes in order to complete the requirements for a doctorate; a dissertation. 

How often have the words chalk talk and doctoral thesis occurred in a corpus of books? (source: Google Ngram Viewer )