probation vs trial run

probation

noun
  • A testing period of time 

  • A period of time when a person occupies a position only conditionally and may easily be removed for poor performance 

  • A type of sentence where convicted criminals are allowed to continue living in the community but will automatically be sent to jail if they violate certain conditions 

trial run

noun
  • An empirical test of the suitability or effectiveness of a method or thing by running it at least once. 

  • An empirical test of the suitability or capability of a person or actor by letting him perform at least once. 

How often have the words probation and trial run occurred in a corpus of books? (source: Google Ngram Viewer )