effectivity vs instrument

effectivity

noun
  • A measure of the effectiveness of something. 

  • [Technical documentation] An indication of the product, procedure, or timescale for which an item of information is applicable or effective. 

  • The ability or power to be effective. 

instrument

noun
  • A means or agency for achieving an effect. 

  • A legal document, such as a contract, deed, trust, mortgage, power, indenture, or will. 

  • A device used to produce music. 

  • A tool, implement used for manipulation or measurement. 

  • A person used as a mere tool for achieving a goal. 

  • A measuring or displaying device. 

verb
  • To devise, conceive, cook up, plan. 

  • To perform upon an instrument; to prepare for an instrument. 

  • To apply measuring devices. 

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