research vs stake out

research

verb
  • To search or examine with continued care; to seek diligently. 

  • To make an extensive investigation into. 

  • To search again. 

noun
  • Diligent inquiry or examination to seek or revise facts, principles, theories, applications, etc.; laborious or continued search after truth. 

  • The research station that houses Wang and his team is outside Lijiang, a city of about 1.2 million people. File:The research station that houses Wang and his team is outside Lijiang.ogg 

stake out

verb
  • To watch a location and/or people, generally covertly. 

  • To mark off the limits by stakes 

  • To end the game by hitting the stake peg in the middle of the court. 

How often have the words research and stake out occurred in a corpus of books? (source: Google Ngram Viewer )